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Objectives To describe the development, validation and reliability of the Oxford Vaccine Hesitancy Scale (OVHS), a new instrument to assess vaccine hesitancy in the general population.Design Cross-sectional validation study.Setting Internet-based study with participants in the UK and USA.Participants Demographically representative (stratified by age, sex and race) samples from the UK and USA recruited through the Prolific Academic platform.Main outcome measures To demonstrate OVHS development, exploratory factor analysis with categorical variables and a polychoric correlation matrix followed by promax oblique rotation on the UK sample was performed. Confirmatory factor analysis with a Satorra-Bentler scaled test statistic evaluating goodness of fit statistics including the root mean squared error of approximation (RMSEA), standardised root mean squared residual (SRMR) and comparative fit index (CFI) was performed on the US sample. Reliability as internal consistency was assessed using McDonald’s omega. Evidence in support of the predictive, convergent and discriminant validity of the scale was assessed using logistic regression ORs of association (OR) or Pearson correlation coefficients.Results Data for factor analysis were obtained from 1004 respondents, 504 in the UK and 500 in the USA. A scree plot, minimum average partial correlation analysis and parallel analysis suggested a three-factor 13-item scale with domains of vaccine beliefs (seven items), pain (three items) and personal deliberation (three items). Responses were recorded on a Likert scale ranging from disagree completely to agree completely, with higher score reflecting greater hesitancy. Potential total scores ranged from 13 to 65. Goodness of fit was excellent, with RMSEA=0.044, SRMR=0.041 and CFI=0.977. Predictive validity for COVID-19 vaccination status was excellent, with logistic regression ORs of association (95% CI) of 0.07 (0.04, 0.13), p

Background Vaccination of infants with pneumococcal conjugate vaccines is recommended by the World Health Organization. Evidence is mixed regarding the differences in immunogenicity and efficacy of the different pneumococcal vaccines. Objectives The primary objective was to compare the immunogenicity of pneumococcal conjugate vaccine-10 versus pneumococcal conjugate vaccine-13. The main secondary objective was to compare the seroefficacy of pneumococcal conjugate vaccine-10 versus pneumococcal conjugate vaccine-13. Methods We searched the Cochrane Library, EMBASE, Global Health, MEDLINE, ClinicalTrials.gov and trialsearch.who.int up to July 2022. Studies were eligible if they directly compared either pneumococcal conjugate vaccine-7, pneumococcal conjugate vaccine-10 or pneumococcal conjugate vaccine-13 in randomised trials of children under 2 years of age, and provided immunogenicity data for at least one time point. Individual participant data were requested and aggregate data used otherwise. Outcomes included the geometric mean ratio of serotype-specific immunoglobulin G and the relative risk of seroinfection. Seroinfection was defined for each individual as a rise in antibody between the post-primary vaccination series time point and the booster dose, evidence of presumed subclinical infection. Each trial was analysed to obtain the log of the ratio of geometric means and its standard error. The relative risk of seroinfection (‘seroefficacy’) was estimated by comparing the proportion of participants with seroinfection between vaccine groups. The log-geometric mean ratios, log-relative risks and their standard errors constituted the input data for evidence synthesis. For serotypes contained in all three vaccines, evidence could be synthesised using a network meta-analysis. For other serotypes, meta-analysis was used. Results from seroefficacy analyses were incorporated into a mathematical model of pneumococcal transmission dynamics to compare the differential impact of pneumococcal conjugate vaccine-10 and pneumococcal conjugate vaccine-13 introduction on invasive pneumococcal disease cases. The model estimated the impact of vaccine introduction over a 25-year time period and an economic evaluation was conducted. Results In total, 47 studies were eligible from 38 countries. Twenty-eight and 12 studies with data available were included in immunogenicity and seroefficacy analyses, respectively. Geometric mean ratios comparing pneumococcal conjugate vaccine-13 versus pneumococcal conjugate vaccine-10 favoured pneumococcal conjugate vaccine-13 for serotypes 4, 9V and 23F at 1 month after primary vaccination series, with 1.14- to 1.54-fold significantly higher immunoglobulin G responses with pneumococcal conjugate vaccine-13. Risk of seroinfection prior to the time of booster dose was lower for pneumococcal conjugate vaccine-13 for serotype 4, 6B, 9V, 18C and 23F than for pneumococcal conjugate vaccine-10. Significant heterogeneity and inconsistency were present for most serotypes and for both outcomes. Twofold higher antibody after primary vaccination was associated with a 54% decrease in risk of seroinfection (relative risk 0.46, 95% confidence interval 0.23 to 0.96). In modelled scenarios, pneumococcal conjugate vaccine-13 or pneumococcal conjugate vaccine-10 introduction in 2006 resulted in a reduction in cases that was less rapid for pneumococcal conjugate vaccine-10 than for pneumococcal conjugate vaccine-13. The pneumococcal conjugate vaccine-13 programme was predicted to avoid an additional 2808 (95% confidence interval 2690 to 2925) cases of invasive pneumococcal disease compared with pneumococcal conjugate vaccine-10 introduction between 2006 and 2030. Limitations Analyses used data from infant vaccine studies with blood samples taken prior to a booster dose. The impact of extrapolating pre-booster efficacy to post-booster time points is unknown. Network meta-analysis models contained significant heterogeneity which may lead to bias. Conclusions Serotype-specific differences were found in immunogenicity and seroefficacy between pneumococcal conjugate vaccine-13 and pneumococcal conjugate vaccine-10. Higher antibody response after vaccination was associated with a lower risk of subsequent infection. These methods can be used to compare the pneumococcal conjugate vaccines and optimise vaccination strategies. For future work, seroefficacy estimates can be determined for other pneumococcal vaccines, which could contribute to licensing or policy decisions for new pneumococcal vaccines. Study registration This study is registered as PROSPERO CRD42019124580. Funding This award was funded by the National Institute for Health and Care Research (NIHR) Health Technology Assessment programme (NIHR award ref: 17/148/03) and is published in full in Health Technology Assessment; Vol. 28, No. 34. See the NIHR Funding and Awards website for further award information. Plain language summary Pneumococcal disease is a serious illness caused by a bacterial infection that can result in death. Children in the United Kingdom receive a vaccine to prevent this disease that protects against 13 different types of pneumococcal diseases. It is very effective, but other vaccines are also available, such as one that contains 10 types of pneumococcal diseases. Vaccines in the United Kingdom are bought by the government and the choice of which vaccine to provide is based on the cost of the vaccine as well as the benefits to our health. However, there is very little information comparing different vaccines and it is often assumed they are the same. We did a large analysis combining all studies of the two main licensed pneumococcal vaccines to determine which vaccine provides better protection against infection and how this affects costs. We used information from studies published in medical journals, and also data from studies done by the companies that own the vaccines. Our results showed that pneumococcal conjugate vaccine-13 vaccine provided better protection than pneumococcal conjugate vaccine-10 for 5 of the 10 serotypes that are contained in both vaccines. When we used these results to model what might have happened had either of these vaccines been introduced into the United Kingdom vaccination programme in 2006, we found that both vaccines caused a rapid decrease in the amount of disease, but that the decrease in disease was faster with pneumococcal conjugate vaccine-13 than pneumococcal conjugate vaccine-10. This resulted in 2808 cases of diseases prevented over a 25-year time frame with pneumococcal conjugate vaccine-13 compared with pneumococcal conjugate vaccine-10. Our methods can be used to compare other vaccines and we recommend this type of study be done in future when making decisions on vaccine product choice. Scientific summary Streptococcus pneumoniae (pneumococcus) causes severe diseases, including bacterial pneumonia, meningitis and sepsis, leading to substantial morbidity and mortality worldwide, with the highest disease burden being in young children and older adults. Three pneumococcal conjugate vaccines (PCVs) have been widely deployed worldwide in the past two decades: PCV7 (Prevnar; Pfizer, headquartered in New York City, New York, USA), PCV10 (Synflorix; GlaxoSmithKline, headquartered in Brentford, London, UK) and PCV13 (Prevenar 13; Pfizer, headquartered in New York City, New York, USA), resulting in substantial reduction in disease. Between 2009 and 2011, PCV7 was gradually replaced by PCV13 and PCV10 and is no longer available. The World Health Organization (WHO) does not preferentially endorse one PCV over another. Both PCV13 and PCV10 have been shown to provide both direct and indirect protection against pneumococcal pneumonia, invasive pneumococcal disease and nasopharyngeal carriage. Although there are 10 common serotypes in these 2 vaccines, the components of the vaccines differ, with different carrier proteins used in the conjugation process, as well as different amounts of polysaccharide, and these differences may contribute to differences in protection. Large randomised controlled trials directly comparing different PCVs with invasive pneumococcal disease as the primary outcome are not feasible. We previously used ‘seroinfection’ as an outcome for analysis of PCVs, where seroinfection is defined as an increase in antibody levels between the primary vaccination series (typically complete at 5–7 months of age) and the booster dose (typically administered at 9–18 months of age). Seroinfection can be regarded as evidence of exposure to the pathogen and a resultant subclinical infection, given antibody responses wane rapidly during this period otherwise. Seroinfection rates for different vaccines can be compared by calculating the relative risk (RR) of seroinfection, referred to herein as ‘seroefficacy’. We meta-analysed data from studies of PCVs to compare the immunogenicity and seroefficacy of PCV10 with PCV13 for each serotype. We aimed to determine if serotype-specific immune responses were higher for either vaccine and whether this resulted in greater protection again seroinfection. In addition, we explored the overall relationship between the higher immune response and protection against seroinfection in infants. Following this, we show how serotype-specific estimates of seroefficacy can be incorporated in vaccine cost-effectiveness models. Objectives The primary objective of the systematic review was to compare the immunogenicity of PCV10 versus PCV13 for each serotype contained in the vaccines. The secondary objectives were: to compare the seroefficacy of PCV10 versus PCV13 for each serotype contained in the vaccines for PCV10 and PCV13 separately, to estimate immunogenicity and seroefficacy in comparison with the older PCV7 vaccine to determine how the comparisons of immunogenicity and efficacy of PCV10 to PCV13 are affected by the co-administration of different routine vaccines. Methods Systematic review We conducted a systematic review identifying studies that compared the immunogenicity of licensed PCVs in trials which randomised children to one of two different PCVs. The PCVs included in the review were PCV7 (Prevnar; Pfizer), PCV10 (Synflorix; GlaxoSmithKline) and PCV13 (Prevenar 13; Pfizer); PCV7 was included even though no longer available, so that we could compare PCV13 and PCV10 indirectly through them each being compared with PCV7 for the same serotypes. Data sources The databases searched were Cochrane Database of Systematic Reviews and Cochrane Central Register of Controlled Trials, EMBASE, Global Health and MEDLINE. The trial registers searched were ClinicalTrials.gov (https://clinicaltrials.gov/) and WHO International Clinical Trials Registry Platform (https://trialsearch.who.int/). The search comprised title/abstract keywords and subject headings for pneumococcal vaccines and children. A methodological search filter for randomised controlled trials taken from the Cochrane Handbook was used to limit to randomised controlled trials. Pharmaceutical company websites (GlaxoSmithKline and Pfizer) were also hand-searched for relevant studies. No date or language limits were applied. Study selection Randomised controlled trials were included if they provided direct comparisons of either PCV7, PCV10 or PCV13 among infants and children ˂ 2 years of age, and if they provided estimates of antibody responses [serotype-specific anti-pneumococcal immunoglobulin G (IgG) to PCVs for at least one time point of 1] between 4 and 6 weeks after the primary vaccination series and/or 1 month after a booster vaccination. Individual participant-level data were retrieved if available. Aggregate data from publications were extracted if individual participant data were not available. Risk of bias in results of the included studies was assessed independently by two reviewers using the Cochrane Risk of Bias Tool. Data synthesis Each trial with individual participant-level data available was analysed to obtain the log of the ratio of geometric means (log-GMR) and its standard error (SE) for each serotype and time point of interest. The RR of seroinfection was estimated by comparing the proportion of participants with seroinfection between vaccine groups. When no seroinfection occurred in any group (numerator of absolute risk was 0), a small non-zero value (0.5) was added to both sero-infected and sero-non-infected groups to allow estimation of the RR. The log-GMRs, log-RRs and their SEs constituted the input data for evidence synthesis. Only trials supplying individual participant data were included in seroefficacy analyses. For serotypes contained in all three vaccines, evidence could be synthesised using a network meta-analysis (NMA) of all comparisons. For other serotypes, meta-analysis was used for evidence synthesis. To estimate the overall association between antibody geometric mean ratio (GMR) and RR across all serotypes, we fitted a mixed-effect model regressing study-level RRs of seroinfection on GMRs across serotypes, weighted by the sample size of each study. Fixed effects included GMR, serotype and interactions between GMR and serotype (allowing serotype-specific association), while study was included as a random effect. Mathematical modelling and retrospective economic evaluation To illustrate the use of serotype-specific estimates of seroefficacy in modelling vaccine impact and cost-effectiveness, we developed a serotype-specific mathematical model of pneumococcal transmission dynamics to compare the differential impact of PCV10 and PCV13 introduction on invasive pneumococcal disease cases with vaccine serotypes in England and Wales. The model estimated the impact over a 25-year time period from 2006 to 2030. We subsequently assessed the cost-effectiveness of introducing infant vaccination with PCV13 compared with introducing PCV10 from a healthcare payer perspective in England and Wales. More specifically, we retrospectively estimated the additional threshold price per dose below which PCV13 would be more cost-effective than PCV10 had they both been available at the time of introduction of the PCV vaccine programme in England and Wales in 2006. Results Database registry and hand searches identified 4699 publication records of which 47 studies (78 publication reports) satisfied our eligibility criteria. Nineteen studies (24 publication reports) were excluded from the analysis: 6 studies did not provide individual patient or aggregate data and 13 studies (18 publication reports) were studies with the vaccines of interest, but it was not possible to form a loop within the NMA to provide indirect evidence. The remaining 28 studies (54 publication records) from 2009 to 2023 were included in the NMAs. Twenty-two studies provided individual participant data with a further five studies reporting aggregate data. Immunogenicity Geometric mean ratios for comparisons between PCV13 versus PCV10 for any primary series schedule were higher for PCV13 for serotypes 4, 7F, 9V and 23F at 1 month after primary vaccination series, with 1.14- to 1.54-fold higher IgG responses with PCV13. Additional serotypes contained only in the PCV13 vaccine (3, 6A and 19A) also favoured PCV13 as expected. GMRs were similar for the remaining serotypes (1, 5, 6B, 14, 18C and 19F). GMRs favoured PCV7 over either PCV13 or PCV10 for serotypes 4, 6B, 9V, 14 and 23F. There was no difference in GMRs for serotypes 18C and 19F across three vaccines. At the pre-booster time point, data were available from 18 cohorts. IgG responses were lower with PCV13 compared with PCV10 for all PCV7 serotypes except for serotype 14, with the point estimates of GMRs comparing PCV13 versus PCV10 ranging from 0.44 to 0.78. IgG responses were higher for PCV13 for serotypes 1, 5 and 7F. GMRs comparing PCV13 versus PCV7 showed higher IgG with PCV7 for serotypes 4, 6B, 9V, 14 and 23F and higher IgG with PCV13 for serotype 19F. At 28 days post booster, data were available from 26 cohorts. GMRs favoured PCV13 over PCV10 for serotype 6B, 9V, 14 and 23F and favoured PCV10 over PCV13 for serotype 18C. For serotype 1, 5 and 7F, antibody responses were higher in PCV13 compared with PCV10. PCV7 recipients had higher geometric mean concentrations (GMCs) compared with PCV13 for all PCV7 serotypes except 6B for which there was no difference, and 19F, which favoured PCV13. For PCV13-only serotypes (3, 6A and 19A), GMRs favour PCV13 at all three time points. Substantial heterogeneity and network inconsistency were present for most serotypes at all three time points. To explore potential reasons for the observed heterogeneity, we summarised cohort-level GMRs and RRs for each vaccine comparison. These descriptive analyses revealed a lack of consistency in the direction of study-level estimates within each vaccine comparison, resulting in the significant heterogenicity. There was also no observable pattern in any trial-level variable (region, co-administered vaccines, vaccine schedule), from which one might propose a mechanism that would adequately explain this variation in GMRs. Seroefficacy There were 12 studies (15 cohorts) with available individual participant antibody data at both post-primary and prior to the booster dose, allowing serotype-specific estimation of seroefficacy from a total of 5152 participants. Of these 15 cohorts, 6 compared PCV10 versus PCV7, 3 compared PCV13 versus PCV7 and 6 compared PCV13 versus PCV10. Among PCV7 serotypes, the risk of seroinfection was lower with PCV13 than PCV10 for serotypes 4, 6B, 9V, 18C and 23F, while no difference was seen for serotype 14 and 19F. The RRs of seroinfection (PCV13 vs. PCV10) for PCV7 serotypes ranged from 0.32 (95% CI 0.19 to 0.52) for serotype 4 to 1.28 (95% CI 0.95 to 1.74) for serotype 14. For serotypes 1, 5 and 7F, evidence was summarised from six studies directly comparing PCV13 with PCV10. Comparisons between PCV13 and PCV7 favoured neither vaccine over the other, whereas comparisons between PCV7 and PCV10 favoured PCV7 for serotypes 5, 6B, 9V, 18C and 23F. The I2 and p-values indicated some heterogeneity for all PCV7 serotypes except for serotype 4 and 19F. In the mixed-effects model of all serotypes combined, vaccines that produced the same amount of antibody (GMR = 1) had very similar protection (adjusted RR 0.80, 95% CI 0.41 to 1.58). The model estimate indicates that for each twofold increase in antibody response, the risk of seroinfection was halved (GMR of 2.0; RR 0.46, 95% CI 0.23 to 0.96). Mathematical model and economic evaluation Mathematical model results showed that in the absence of any vaccine programme, an increase in invasive pneumococcal disease cases caused by all five serotypes would be seen over the 25-year time frame. With the introduction of either PCV13 or PCV10 vaccine programmes in 2006, case counts would have decreased, achieving near eradication of all serotypes within the time frame modelled. The decrease in cases was most rapid for serotype 6B and least rapid for serotype 4. The decrease in cases was less rapid for PCV10 than for PCV13 due to the lower seroefficacy. The introduction of an infant PCV13 programme was predicted to avoid an additional 2808 (95% CI 2690 to 2925) cases of invasive pneumococcal disease compared with PCV10 introduction between 2006 and 2030. This includes an estimated 326 cases of meningitis, 578 cases of sepsis, 1770 cases of invasive pneumonia and 30,680 cases of non-invasive pneumonia. Under base-case assumptions, this resulted in discounted healthcare savings of £13 million (95% CI £12 to £14 million). Including non-invasive pneumonia increased the savings to £27 million (95% CI £25 to £29 million). Conclusions In our study, we used a novel methodology to define seroinfection from immunogenicity data to compare the relative efficacy of PCVs in preventing infection. Our results using individual-level data from a global meta-analysis provide the first estimates of the comparative protection afforded by different pneumococcal vaccines and show that for many serotypes, carriage events are less common after PCV13 than PCV10, likely due to a higher antibody response. In addition, we quantify the relationship between the immune response to vaccination and protection against infection, measured serologically, and show that higher antibody responses in infants are associated with greater protection from infection. Licensure of new vaccines is based on non-inferiority comparisons with current vaccines and the proportion of antibody responses above the agreed threshold as a minimum requirement. Once a vaccine meets this ‘at-least-as-good-as’ immunogenicity criteria, it has previously not been clear whether exceeding it is of benefit, and the WHO position paper on pneumococcal vaccines states ‘It is unknown whether a lower serotype-specific GMC of antibody indicates less efficacy’. Our results show that lower protection against subclinical infection does indeed follow from lower antibody production and that two vaccines that produce a similar level of antibody will provide similar levels of protection. The implications of these findings are of greatest importance when a new vaccine roll-out is being considered. Lower antibody production or lower seroefficacy for one vaccine product does not necessarily imply limited effectiveness against invasive pneumococcal diseases when considering vaccines such as PCV10 and PCV13 which are highly effective vaccines in many settings. Instead, lower antibody responses lead to less rapidly observed indirect protection after implementation into a national programme as a smaller proportion of transmission events are blocked by the vaccine. This is evident in the mathematical modelling which showed less rapid decreases in the number of cases of invasive disease when introducing PCV10 compared with PCV13. Implications for practice This evidence of differences in serotype-specific protection can be incorporated into cost-effectiveness models used to compare vaccine products. Cost-effectiveness studies have highlighted the lack of evidence of comparative efficacy for different PCVs, resulting in previous cost-effectiveness models that ignore serotype-specific differences and assume equivalent efficacy for all serotypes covered by different PCVs. Our study fills this evidence gap and allows researchers and policy-makers to use more accurate vaccine-specific models in decision-making. Our cost-effectiveness analysis of a hypothetical scenario showed that introducing infant PCV13 was predicted to avert a higher burden of pneumococcal disease compared with PCV10. This would have realised a small saving of £13 million discounted over 24 years. When considering the introduction of new pneumococcal vaccines into the routine immunisation schedule, we recommend that differences in antibody responses for different vaccines be considered in modelling scenarios as higher antibody responses result in reduced transmission and greater impact on invasive diseases. Vaccine-specific threshold prices can then be determined for cost-effective vaccines. Our analysis showed that due to its higher efficacy against some serotypes, a higher threshold price per dose could be paid for PCV13 while remaining cost-effective. Study registration This study is registered as PROSPERO CRD42019124580. Funding This award was funded by the National Institute for Health and Care Research (NIHR) Health Technology Assessment programme (NIHR award ref: 17/148/03) and is published in full in Health Technology Assessment; Vol. 28, No. 34. See the NIHR Funding and Awards website for further award information.

Background There are data suggesting that intravenous immunoglobulin treatment has some benefit for certain forms of encephalitis but robust evidence from large randomised controlled trials in children with all-cause encephalitis is lacking. Objective To evaluate whether intravenous immunoglobulin treatment improves neurological outcomes in childhood encephalitis when given early in the illness. Design Phase 3b, investigator-initiated, randomised, double-blind, placebo-controlled trial of intravenous immunoglobulin for the treatment of encephalitis in children. Setting Twenty-one NHS Hospitals in the UK. Participants Children aged 6 months to 16 years with a diagnosis of acute or sub-acute encephalitis. Intervention Two doses (1 g/kg/dose) of either intravenous immunoglobulin or matching placebo, given 24–36 hours apart, in addition to standard treatment. Main outcome measure Participants were followed up for 12 months (+/– 4 weeks) after randomisation. The primary outcome measure was a ‘good recovery’ defined as a score of ≤ 2 on the Paediatric Glasgow Outcome Score Extended at 12 months after randomisation. Secondary outcomes The secondary outcomes were clinical, neurological, neuroimaging and neuropsychological results, identification of the proportion of children with immune-mediated encephalitis, and intravenous immunoglobulin safety data. Results We planned to recruit 308 children over a 42-month period. After enrolment of 18 participants (8 male; 44%) over 21 months (from December 2015 to September 2017), funding was withdrawn due to slow recruitment and the study was terminated. Ten participants were randomised to the intravenous immunoglobulin group, and eight to the placebo group, and all 18 participants were included in the analysis. At 12 months after randomisation, 9 participants [50%; intravenous immunoglobulin n = 5 (50%), placebo n = 4 (50%)] made good recovery and 5 participants [28%; intravenous immunoglobulin n = 3 (30%), placebo n = 2 (25%)] made a poor recovery. Three participants in the placebo group (43%) experienced a total of 10 serious adverse events compared with none in the intravenous immunoglobulin group but none of the adverse events were judged to be related to the study treatment. No deaths occurred during the study period. Conclusion ImmunoglobuliN in the Treatment of Encephalitis (IgNiTE) was halted prematurely due to slow recruitment. Given the small sample size, the study was underpowered to evaluate the effect of intravenous immunoglobulin when compared with placebo in childhood encephalitis. The study findings, albeit from a small sample size, support existing evidence that encephalitis results in poor neurological outcomes for many children. Lessons learned from the ImmunoglobuliN in the Treatment of Encephalitis trial would be valuable for the success of future trials set up to address the efficacy of early treatment with intravenous immunoglobulin in all-cause encephalitis in children. Study limitations and future work The study was underpowered to evaluate the efficacy of intravenous immunoglobulin in the treatment of childhood encephalitis due to the small sample size achieved. Future trials should seek to address this important question. Trial registration This trial is registered as Clinical Trials.gov (NCT02308982) and ISRCTN15791925. Funding This award was funded by the National Institute for Health and Care Research (NIHR) Efficacy and Mechanism Evaluation (EME) programme (NIHR award ref: 12/212/15) and is published in full in Efficacy and Mechanism Evaluation; Vol. 11, No. 6. See the NIHR Funding and Awards website for further award information. Plain language summary Encephalitis (inflammation of the brain) is a serious but rare condition affecting approximately 5 in 100,000 children in England. Encephalitis can have a big impact on affected children and their families. Approximately 12 out of 100 affected children will die and half of those that survive experience varying difficulties in the long term; these might include problems with memory, physical disabilities, seizures and changes in how they think and behave. There is some evidence that a treatment called intravenous immunoglobulin may benefit people affected by encephalitis. Intravenous immunoglobulin contains antibodies obtained from blood donations by different people, which is used to treat some types of inflammation. However, there have been no research studies investigating the effect of intravenous immunoglobulin when used in large numbers of children with all types of encephalitis. Furthermore, although intravenous immunoglobulin is sometimes used to treat children with encephalitis, it is often given after other treatments have been unsuccessful. Outcomes from encephalitis are determined largely by the amount of brain inflammation; it would therefore seem logical that giving a treatment early in the illness to limit the inflammation would be beneficial. In the ImmunoglobuliN in the Treatment of Encephalitis study, we aimed to find out whether giving intravenous immunoglobulin to children with encephalitis early in the illness can help them get better more quickly and reduce the difficulties they experience later on. Half of the children in the trial received intravenous immunoglobulin and the other half received an inactive medicine, known as placebo, in addition to the normal care they would receive in a hospital. We aimed to compare the recovery and outcomes between children in these two groups. This trial was stopped early due to withdrawal of funding, as fewer children than expected were enrolled into the study. Too few children were enrolled for us to be sure whether intravenous immunoglobulin benefits children with encephalitis. However, the trial findings highlight the impact of encephalitis on affected children, with around half of children demonstrating ongoing difficulties 1 year after the illness. Scientific summary Background There is significant mortality and morbidity from encephalitis in children despite the current standard of care. Thus, strategies to improve outcomes in patients with encephalitis are urgently required. Theoretical and empirical evidence suggest a beneficial role of intravenous immunoglobulin (IVIG) for viral and auto-immune forms of encephalitis. Therefore, we set up a prospective randomised controlled trial (RCT) to ascertain the efficacy of early IVIG treatment for all-cause encephalitis in children. In the study, children with encephalitis were randomised to receive two doses of either IVIG or placebo within five working days from the suspicion of an encephalitis diagnosis, in addition to normal standard of care. They were then followed up for 12 months after randomisation. We hypothesised that IVIG could have therapeutic benefit for children with encephalitis when administered early in the illness. Objectives The primary objective was to evaluate the efficacy of early IVIG treatment in childhood encephalitis. This was assessed by comparing the proportion of children in the 2 treatment groups who made good recovery, assessed using the paediatric version of the Glasgow outcome score extended, at 12 months after randomisation. The secondary objectives were to: (1) compare clinical, neurological, neuroimaging and neuropsychological outcomes between the treatment groups, (2) evaluate the proportion of participants with autoimmune encephalitis and (3) confirm the safety of IVIG. Methods Trial design This was a phase 3b multicentre, double-blind, randomised, placebo-controlled trial to evaluate the early use IVIG in childhood encephalitis. Setting Participants were recruited from 21 NHS Hospitals in the UK. Participants Inclusion criteria Participants were eligible if they were aged between 6 weeks and 16 years they met the case definition for possible encephalitis based on the International Encephalitis Consensus parents/guardians provided written informed consent, or assent if appropriate. Exclusion criteria The exclusion criteria included: (1) a high clinical suspicion of bacterial meningitis, (2) prior receipt of IVIG during the admission or known contraindication to IVIG, (3) traumatic brain injury, (4) history of metabolic encephalopathy, stroke, toxic or hypertensive encephalopathy, (5) pre-existing demyelinating disorder, (6) significant renal impairment, (7) hypercoagulable state, (8) hyperprolinaemia, (9) participation in another research trial involving an immunomodulatory treatment, (10) known to be pregnant, (11) any significant disease or clinical research that would impact on participation, or interfere with compliance with study requirements. Randomisation Participants were randomly assigned 1 : 1 ratio to receive 2 doses (1 g/kg/dose) of either IVIG or matching placebo, in addition to standard care. Randomisation was stratified by age and receipt of steroid treatment. Interventions Two doses of 1 g/kg/dose of either IVIG or a matching volume of placebo were given 24–36 hours apart, with the first dose administered as soon as possible after enrolment and within five working days from the suspicion of an encephalitis diagnosis. The active treatment (IVIG) used in the study was Privigen (100 mg/ml solution), manufactured and provided by CSL Behring. The placebo was a mixture of 0.9% saline + 0.1% human albumin solution, manufactured at the Royal Broadgreen and Liverpool Aseptic Production Unit, Liverpool, UK, under current good manufacturing practice conditions and its Manufacturer’s Importer’s Authorisation licence. The addition of albumin to saline was necessary to make the placebo visually identical to IVIG. Blinding Participants, treating clinicians, parents/guardians and outcome assessors were blinded to the allocated treatment. Primary outcome The primary outcome was good recovery (i.e. score of ≤2) on the paediatric version of the Glasgow Outcome Score-Extended (GOS-E Peds) at 12 months after randomisation. Secondary outcomes Clinical, neurological and neuropsychological outcomes Multiple clinical and neurological measures were collected during the hospital admission, at 4–8 weeks after discharge from acute care, and at 6 and 12 months after randomisation. A blinded neuropsychologist assessment of cognitive function was carried out at 12 months after randomisation. Radiological outcomes Brain magnetic resonance imaging (MRI) findings at 6 months after randomisation were compared with imaging results obtained during the acute illness. Safety data Safety and adverse events (AEs) data were collected until 12 months after randomisation. Identification of immune-mediated encephalitis Presence of specific auto-antibodies in serum was assessed. Statistical methods The analyses were performed on the intention-to-treat population; this included all participants who were randomised, irrespective of study treatment received. In the analysis of the AEs, all participants who received study treatment were included. Since 20% of participants were recruited before the trial was halted, all analyses are descriptive. Results Recruitment took place between 23 December 2015 and 26 September 2017. Recruitment was paused in September 2017 following withdrawal of funding due to slower than anticipated recruitment. Despite strategies implemented to improve recruitment, funding was not reinstated. Attempts at securing alternative funding were unsuccessful; therefore, the trial was closed on 24 October 2017. Participants and demographics At the time of halting the study, 18 participants had been randomised (IVIG n = 10; placebo n = 8). One participant each from the IVIG and placebo groups were withdrawn from the study before receipt of study treatment and one participant in the placebo arm refused a second dose of study treatment. Therefore 16 participants (IVIG n = 9; placebo n = 7) received at least one dose of the study treatment and 15 participants (IVIG n = 9, placebo n = 6) received two full doses of the study treatment. One participant in the placebo group was lost to follow up after the 6 months visit and 1 participant in the IVIG group withdrew consent prior to the visit 12 months after randomisation. The median age at randomisation was 4.09 years [interquartile range (IQR) = 2.0–11.8], 44% were male and 89% were of white ethnicity. Baseline characteristics were well matched across treatment arms. Primary outcome At 12 months after randomisation, 9 participants [50%; IVIG n = 5 (50%); placebo n = 4 (50%)] made a good recovery (score ≤2 on the GOS-E Peds) and 5 participants [28%; IVIG n = 3 (30%), placebo n = 2 (25%)] made a poor recovery (score > 2). Four participants (22%; IVIG n = 2 (20%), placebo n = 2 (25%)] did not undergo a GOS-E Peds assessment at 12 months after randomisation. Secondary outcomes Inpatient data Ten participants [56%; IVIG n = 5 (50%), placebo = 5 (63%)] were admitted to intensive care, and nine of these [90%; IVIG n = 4 (80%), placebo n = 5(100%)] required invasive ventilation, for a median duration of two days (IQR 2.0–3.0). The median length of stay on intensive care was 4.5 days (3.0–6.8) and the overall median length of hospitalisation for acute care was 11 days (7.8–19.5). Epilepsy diagnosis Three participants [17%; IVIG n = 1 (10%), placebo n = 2 (25%)] had a new diagnosis of epilepsy during the study period. Five participants [28%; IVIG n = 2 (20%), placebo n = 3 (38%)] had incomplete data for this outcome. Glasgow Outcome Score-Extended-Peds at 6 months after randomisation Eight participants [44%; IVIG n = 4 (40%), placebo n = 4 (50%)] made a good recovery at 6 months after randomisation, whereas seven participants [39%; IVIG n = 4 (50%), placebo n = 3 (38%)] made a poor recovery. Three participants [17%; IVIG n = 2 (20%), placebo n = 1 (13%)] did not undergo a GOS-E Peds assessment at 6 months after randomisation. Liverpool outcome score At 4–8 weeks after discharge from acute care, 5 participants [28%; IVIG n = 3 (30%), placebo n = 2 (25%)] made a full recovery [defined as a Liverpool Outcome Score (LOS) of >4], whereas 10 participants [56%; IVIG n = 5 (50%), placebo n = 5 (63%)] had minor to severe sequelae. Three participants [17%; IVIG n = 2 (20%); placebo n = 1 (13%)] did not have LOS data collected at this timepoint. At 12 months after randomisation, six participants [33%; IVIG n = 4 (40%), placebo n = 2 (25%)] made full recovery on the LOS assessment, while 8 participants [44%; IVIG n = 4 (40%), placebo n = 4 (50%)] reported minor to severe sequelae. Four participants [22%; IVIG n = 2 (20%); placebo n = 2 (25%)] did not have LOS data collected at this timepoint. Paediatric quality of life assessment Paediatric quality of life scores were available for seven participants [39%; IVIG n = 5 (50%), placebo n = 2 (25%)] at 4–8 weeks after discharge from acute care and for eight participants [44%; IVIG n = 6 (60%), placebo n = 2 (25%)] at 12 months post randomisation. At 4–8 weeks after discharge from acute care, the mean PedsQL score was 77.9 (standard deviation, SD, 11.10) and 56.5 (SD 7.8) for the IVIG and placebo group, respectively. At 12 months, mean PedsQL scores were 79.9 (SD 21.6) and 63.7 (SD 30.1) for the IVIG and placebo groups, respectively. Gross motor function classification system At 4–8 weeks after discharge from acute care, seven participants [39%; IVIG n = 5 (50%); placebo n = 2 (25%)] had mild impairment of gross motor functioning. These data were not available for 11 participants [61%; IVIG n = 5 (50%), placebo n = 6 (75%)] at this timepoint. At 12 months after randomisation, eight participants [44%; IVIG n = 6 (60%); placebo n = 2 (25%)] experienced mild or severe impairment of gross motor function. These data were not available for ten participants [56%; IVIG n = 4 (40%), placebo n = 6 (75%)] at this timepoint. Strengths and difficulties assessment Strengths and Difficulties Questionnaire (SDQ) results were available for seven participants (IVIG n = 5, placebo n = 2) at 4–8 weeks after discharge from acute care and eight participants (IVIG n = 6, placebo n = 2) at 12 months after randomisation. At 4–8 weeks after discharge from acute care, five participants [28%; IVIG n = 4 (40%); placebo n = 1 (13%)] had a close to average SDQ score, one participant [6%, IVIG n = 1 (10%), placebo n = 0] had a slightly raised SDQ score and one participant [6%, IVIG n = 0, placebo n = 1 (13%)] had a very high SDQ score. At 12 months after randomisation, the same number of participants had a close to average score and slightly raised score, but two participants [11%; IVIG n = 1 (10%), placebo n = 1 (13%)] had a very high SDQ score. Adaptive Behaviors Assessment System – second edition At 4–8 weeks after discharge from acute care, five participants [28%; IVIG n = 4 (40%), placebo n = 1 (13%)] had an Adaptive Behaviors Assessment System-second edition (ABAS-II) score that was either similar or higher than the average score of the normative population. At the same time point, three participants [17%; IVIG n = 2 (20%), placebo n = 1 (13%)] had a score that was lower than the average score. Ten participants [56%; IVIG n = 4 (40%), placebo n = 6 (75%)] did not have ABAS-II assessment at this timepoint. At 12 months after randomisation, the same number of participants had a score that was below the average, but four participants [22%; IVIG n = 3 (30%), placebo n = 1 (13%)] had a score that was either similar or higher than the average score, and 11 participants [61%; IVIG n = 5 (50%), placebo n = 6 (75%)] did not have ABAS-II assessment at this timepoint. Neuropsychology assessment Thirteen participants (72%; IVIG n = 8 (80%); placebo n = 5 (63%)] had blinded neuropsychology assessment at 12 months after randomisation; four [30%; IVIG n = 2 (25%), placebo n = 2 (40%)] of these participants were unable to complete the full battery of assessments due to attention or behavioural needs. Five participants [28%; IVIG n = 2 (20%), placebo n = 3 (38%)] did not undergo neuropsychology assessment. Five participants [28%; IVIG n = 4 (40%), placebo n = 1 (13%)] had a score of ≥85 (indicating normal development) for Full-Scale IQ, six [33%; IVIG n = 4 (40%); placebo n = 2 (25%)] for Verbal Comprehension Index (VCI), five [28%; IVIG n = 4 (40%), placebo n = 1 (13%)] for visual spatial; four [22%; IVIG n = 4 (40%), placebo n = 0 (0%)] for working memory index (WMI); and four [22%; IVIG n = 3 (30%); placebo n = 1 (13%)] for Perceptual Reasoning Index (PRI). Two participants (one in each treatment arm) were assessed using the Bayley scale of infant and toddler development, one participant (IVIG arm) had severe neurodevelopmental impairment while the other (placebo arm) had a normal neurodevelopmental outcome. Neuroimaging Nineteen acute neuroimaging scans were available for 13 participants. Five scans (for five unique participants) had abnormal findings; all of these were MRI scans. Four of the abnormal scans showed bilateral lesions. There were nine follow-up scans for eight unique participants of which six scans (for five unique participants) were normal and unchanged from the acute scan. Three follow-up scans (for three unique participants) had abnormal findings; two of these were unchanged from the acute scans and an acute scan was not available for comparison one participant. Autoantibody testing Twelve participants had autoantibody testing. One participant (placebo n = 1) was positive for LGI1 antibodies, and one participant (placebo n = 1) was positive for myelin oligodendrocyte glycoprotein (MOG) antibodies. Two additional participants (IVIG n = 2) were positive for IgG to live neurons, indicating the presence of IgG antibodies binding to neurons, but negative for antibodies to the specific antigens tested for in the study. Safety reporting One participant in the IVIG group reported an AE of special interest; the participant developed a fever during IVIG infusion; however, this was judged to be unrelated to the study treatment. Ten serious AEs occurred in three participants in the placebo group and none in the IVIG group. None of the serious adverse events (SAEs) were judged to be related to the study treatment. No deaths occurred during the study period. Conclusions ImmunoglobuliN in the Treatment of Encephalitis (IgNiTE) was the first RCT to prospectively evaluate the efficacy of IVIG in childhood encephalitis. It was anticipated that data from IgNiTE would provide definitive evidence on which to base the management of children with encephalitis in the UK and worldwide. However, due to slow recruitment, the trial was terminated early. Therefore, the trial did not reach its pre-determined sample size and was underpowered, making it impossible to reach a conclusion on the role of IVIG in treatment of childhood encephalitis. Nonetheless, IgNiTE has highlighted several key learning points. Firstly, IgNiTE has demonstrated the feasibility of setting up a large multi-centre trial efficacy trial in a cohort of children with a rare condition such as encephalitis. Secondly, data from IgNiTE, albeit derived from a small sample size, suggest the safety of IVIG and provide some insight into the burden that encephalitis places on children and the NHS. Over half of the study participants were admitted to the intensive care unit with 90% of those admitted requiring invasive ventilation, with a prolonged overall length of hospitalisation. In addition, a notable proportion of children experienced some degree of disability at follow-up, highlighting the need to prioritise studies aimed at identifying strategies to alleviate the burden from this rare but debilitating disease. For future studies aimed at addressing the efficacy of early IVIG treatment in childhood encephalitis, consideration should be given to practical challenges with setting up RCTs for rare diseases. These include the necessity to recruit from multiple sites to achieve the sample size, the importance of clinical equipoise amongst treating clinicians, and the trade-off between having a stringent but robust set of entry criteria and the impact of this on recruitment. Trial registration This trial is registered as Clinical Trials.gov (NCT02308982) and ISRCTN15791925. Funding This award was funded by the National Institute for Health and Care Research (NIHR) Efficacy and Mechanism Evaluation (EME) programme (NIHR award ref: 12/212/15) and is published in full in Efficacy and Mechanism Evaluation; Vol. 11, No. 6. See the NIHR Funding and Awards website for further award information.

Introduction Invasive non-typhoidal Salmonella (iNTS) serovars are a major cause of community-acquired bloodstream infections in sub-Saharan Africa (SSA). In this setting, Salmonella enterica serovar Typhimurium accounts for two-thirds of infections and is associated with an estimated case fatality rate of 15%–20%. Several iNTS vaccine candidates are in early-stage assessment which—if found effective—would provide a valuable public health tool to reduce iNTS disease burden. The CHANTS study aims to develop a first-in-human Salmonella Typhimurium controlled human infection model, which can act as a platform for future vaccine evaluation, in addition to providing novel insights into iNTS disease pathogenesis.Methods and analysis This double-blind, safety and dose-escalation study will randomise 40–80 healthy UK participants aged 18–50 to receive oral challenge with one of two strains of S. Typhimurium belonging to the ST19 (strain 4/74) or ST313 (strain D23580) lineages. 4/74 is a global strain often associated with diarrhoeal illness predominantly in high-income settings, while D23580 is an archetypal strain representing invasive disease-causing isolates found in SSA. The primary objective is to determine the minimum infectious dose (colony-forming unit) required for 60%–75% of participants to develop clinical or microbiological features of systemic salmonellosis. Secondary endpoints are to describe and compare the clinical, microbiological and immunological responses following challenge. Dose escalation or de-escalation will be undertaken by continual-reassessment methodology and limited within prespecified safety thresholds. Exploratory objectives are to describe mechanisms of iNTS virulence, identify putative immune correlates of protection and describe host–pathogen interactions in response to infection.Ethics and dissemination Ethical approval has been obtained from the NHS Health Research Authority (London—Fulham Research Ethics Committee 21/PR/0051; IRAS Project ID 301659). The study findings will be disseminated in international peer-reviewed journals and presented at national/international stakeholder meetings. Study outcome summaries will be provided to both funders and participants.Trial registration number NCT05870150

Objectives To develop and validate the Oxford Needle Experience (ONE) scale, an instrument to assess needle fear, attitudes and expectations in the general population.Design Cross-sectional validation study.Setting Internet-based with participants in the UK and USA.Participants UK and US representative samples stratified by age, sex, and ethnicity using the Prolific Academic platform.Main outcome measures Exploratory factor analysis with categorical variables and a polychoric correlation matrix followed by promax oblique rotation on the UK sample for the ONE scale. Confirmatory factor analysis (CFA) with a Satorra-Bentler scaled test statistic evaluating the root mean squared error of approximation (RMSEA), standardised root mean squared residual (SRMR) and comparative fit index (CFI) on the US sample. Reliability as internal consistency using McDonald’s omega. Convergent validity using the Pearson correlation coefficient. Predictive and discriminant validity using logistic regression ORs of association (OR).Results The population included 1000 respondents, 500 in the UK and 500 in the USA. Minimum average partial correlation and a scree plot suggested four factors should be retained: injection hesitancy, blood-related hesitancy, recalled negative experiences and perceived benefits, yielding a 19-question scale. On CFA, the RMSEA was 0.070 (90% CI, 0.064 to 0.077), SRMR 0.053 and CFI 0.925. McDonald’s omega was 0.92 and 0.93 in the UK and US samples, respectively. Convergent validity with the four-item Oxford Coronavirus Explanations, Attitudes and Narratives Survey (OCEANS) needle fear scale demonstrated a strong correlation (r=0.83). Predictive validity with a single-question COVID-19 vaccination status question demonstrated a strong association, OR (95% CI) 0.97 (0.96 to 0.98), p

Introduction Invasive non-typhoidal Salmonellosis (iNTS) is mainly caused by Salmonella enterica serovars Typhimurium and Enteritidis and is estimated to result in 77 500 deaths per year, disproportionately affecting children under 5 years of age in sub-Saharan Africa. Invasive non-typhoidal Salmonellae serovars are increasingly acquiring resistance to first-line antibiotics, thus an effective vaccine would be a valuable tool in reducing morbidity and mortality from infection. While NTS livestock vaccines are in wide use, no licensed vaccines exist for use in humans. Here, a first-in-human study of a novel vaccine (iNTS-GMMA) containing S. Typhimurium and S. Enteritidis Generalised Modules for Membrane Antigens (GMMA) outer membrane vesicles is presented.Method and analysis The Salmonella Vaccine Study in Oxford is a randomised placebo-controlled participant-observer blind phase I study of the iNTS-GMMA vaccine. Healthy adult volunteers will be randomised to receive three intramuscular injections of the iNTS-GMMA vaccine, containing equal quantities of S. Typhimurium and S. Enteritidis GMMA particles adsorbed on Alhydrogel, or an Alhydrogel placebo at 0, 2 and 6 months. Participants will be sequentially enrolled into three groups: group 1, 1:1 randomisation to low dose iNTS-GMMA vaccine or placebo; group 2, 1:1 randomisation to full dose iNTS-GMMA vaccine or placebo; group 3, 2:1 randomisation to full dose or lower dose (dependant on DSMC reviews of groups 1 and 2) iNTS-GMMA vaccine or placebo.The primary objective is safety and tolerability of the vaccine. The secondary objective is immunogenicity as measured by O-antigen based ELISA. Further exploratory objectives will characterise the expanded human immune profile.Ethics and dissemination Ethical approval for this study has been obtained from the South Central—Oxford A Research Ethics Committee (Ethics REF:22/SC/0059). Appropriate documentation and regulatory approvals have been acquired. Results will be disseminated via peer-reviewed articles and conferences.Trial registration number EudraCT Number: 2020-000510-14.

Objective To investigate whether intravenous immunoglobulin (IVIG) improves neurological outcomes in children with encephalitis when administered early in the illness.Design Phase 3b multicentre, double-blind, randomised placebo-controlled trial.Setting Twenty-one hospitals in the UK.Participants Children aged 6 months to 16 years with a diagnosis of acute or subacute encephalitis, with a planned sample size of 308.Intervention Two doses (1 g/kg/dose) of either IVIG or matching placebo given 24–36 hours apart, in addition to standard treatment.Main outcome measure The primary outcome was a ‘good recovery’ at 12 months after randomisation, defined as a score of≤2 on the Paediatric Glasgow Outcome Score Extended.Secondary outcome measures The secondary outcomes were clinical, neurological, neuroimaging and neuropsychological results, identification of the proportion of children with immune-mediated encephalitis, and IVIG safety data.Results 18 participants were recruited from 12 hospitals and randomised to receive either IVIG (n=10) or placebo (n=8) between 23 December 2015 and 26 September 2017. The study was terminated early following withdrawal of funding due to slower than anticipated recruitment, and therefore did not reach the predetermined sample size required to achieve the primary study objective; thus, the results are descriptive. At 12 months after randomisation, 9 of the 18 participants (IVIG n=5/10 (50%), placebo n=4/8 (50%)) made a good recovery and 5 participants (IVIG n=3/10 (30%), placebo n=2/8 (25%)) made a poor recovery. Three participants (IVIG n=1/10 (10%), placebo n=2/8 (25%)) had a new diagnosis of epilepsy during the study period. Two participants were found to have specific autoantibodies associated with autoimmune encephalitis. No serious adverse events were reported in participants receiving IVIG.Conclusions The IgNiTE (ImmunoglobuliN in the Treatment of Encephalitis) study findings support existing evidence of poor neurological outcomes in children with encephalitis. However, the study was halted prematurely and was therefore underpowered to evaluate the effect of early IVIG treatment compared with placebo in childhood encephalitis.Trial registration number Clinical Trials.gov NCT02308982; ICRCTN registry ISRCTN15791925.

Background: The Global Typhoid Genomics Consortium was established to bring together the typhoid research community to aggregate and analyse Salmonella enterica serovar Typhi (Typhi) genomic data to inform public health action. This analysis, which marks 22 years since the publication of the first Typhi genome, represents the largest Typhi genome sequence collection to date (n=13,000). Methods: This is a meta-analysis of global genotype and antimicrobial resistance (AMR) determinants extracted from previously sequenced genome data and analysed using consistent methods implemented in open analysis platforms GenoTyphi and Pathogenwatch. Results: Compared with previous global snapshots, the data highlight that genotype 4.3.1 (H58) has not spread beyond Asia and Eastern/Southern Africa; in other regions, distinct genotypes dominate and have independently evolved AMR. Data gaps remain in many parts of the world, and we show the potential of travel-associated sequences to provide informal ‘sentinel’ surveillance for such locations. The data indicate that ciprofloxacin non-susceptibility (>1 resistance determinant) is widespread across geographies and genotypes, with high-level ciprofloxacin resistance (≥3 determinants) reaching 20% prevalence in South Asia. Extensively drug-resistant (XDR) typhoid has become dominant in Pakistan (70% in 2020) but has not yet become established elsewhere. Ceftriaxone resistance has emerged in eight non-XDR genotypes, including a ciprofloxacin-resistant lineage (4.3.1.2.1) in India. Azithromycin resistance mutations were detected at low prevalence in South Asia, including in two common ciprofloxacin-resistant genotypes. Conclusions: The consortium’s aim is to encourage continued data sharing and collaboration to monitor the emergence and global spread of AMR Typhi, and to inform decision-making around the introduction of typhoid conjugate vaccines (TCVs) and other prevention and control strategies. Funding: No specific funding was awarded for this meta-analysis. Coordinators were supported by fellowships from the European Union (ZAD received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 845681), the Wellcome Trust (SB, Wellcome Trust Senior Fellowship), and the National Health and Medical Research Council (DJI is supported by an NHMRC Investigator Grant [GNT1195210]).

Introduction This is the first efficacy study of an oral live attenuated vaccine against Salmonella Paratyphi A using a human challenge model of paratyphoid infection. S. Paratyphi A is responsible for 3.3 million cases of enteric fever every year, with over 19 000 deaths. Although improvements to sanitation and access to clean water are vital to reduce the burden of this condition, vaccination offers a cost-effective, medium-term solution. Efficacy trials of potential S. Paratyphi vaccine candidates in the field are unlikely to be feasible given the large number of participants required. Human challenge models therefore offer a unique, cost-effective solution to test efficacy of such vaccines.Methods and analysis This is an observer-blind, randomised, placebo-controlled trial phase I/II of the oral live-attenuated vaccine against S. Paratyphi A, CVD 1902. Volunteers will be randomised 1:1 to receive two doses of CVD 1902 or placebo, 14 days apart. One month following second vaccination all volunteers will ingest S. Paratyphi A bacteria with a bicarbonate buffer solution. They will be reviewed daily in the following 14 days and diagnosed with paratyphoid infection if the predefined microbiological or clinical diagnostic criteria are met. All participants will be treated with antibiotics on diagnosis, or at day 14 postchallenge if not diagnosed. The vaccine efficacy will be determined by comparing the relative attack rate, that is, the proportion of those diagnosed with paratyphoid infection, in the vaccine and placebo groups.Ethics and dissemination Ethical approval for this study has been obtained from the Berkshire Medical Research Ethics Committee (REC ref 21/SC/0330). The results will be disseminated via publication in a peer-reviewed journal and presentation at international conferences.Trial registration number ISRCTN15485902.

Introduction Inactivated, viral vector and mRNA vaccines have been used in the Nepali COVID-19 vaccination programme but there is little evidence on the effectiveness of these vaccines in this setting. The aim of this study is to describe COVID-19 vaccine effectiveness in Nepal and provide information on infections with SARS-CoV-2 variants.Methods and analysis This is a hospital-based, prospective test-negative case–control study conducted at Patan Hospital, Kathmandu. All patients >18 years of age presenting to Patan Hospital with COVID-19-like symptoms who have received a COVID-19 antigen/PCR test are eligible for inclusion. The primary outcome is vaccine effectiveness of licensed COVID-19 vaccines against laboratory-confirmed COVID-19 disease.After enrolment, information will be collected on vaccine status, date of vaccination, type of vaccine, demographics and other medical comorbidities. The primary outcome of interest is laboratory-confirmed SARS-CoV-2 infection. Cases (positive for SARS-CoV-2) and controls (negative for SARS-CoV-2) will be enrolled in a 1:4 ratio. Vaccine effectiveness against COVID-19 disease will be analysed by comparing vaccination status with SARS-CoV-2 test results.Positive SARS-CoV-2 samples will be sequenced to identify circulating variants and estimate vaccine effectiveness against common variants.Measuring vaccine effectiveness and identifying SARS-CoV-2 variants in Nepal will help to inform public health efforts. Describing disease severity in relation to specific SARS-CoV-2 variants and vaccine status will also inform future prevention and care efforts.Ethics and dissemination Ethical approval was obtained from the University of Oxford Tropical Ethics Committee (OxTREC) (ref: 561-21) and the Patan Academy of Health Sciences Institutional Review Board (ref: drs2111121578). The protocol and supporting study documents were approved for use by the Nepal Health Research Council (NHRC 550-2021). Results will be disseminated in peer-reviewed journals and to the public health authorities in Nepal.

Summary: Background: In Nepal, Streptococcus pneumoniae (pneumococcus) is a common cause of bacterial pneumonia in children, and is a major health concern. There are few data on the effect of vaccination on the disease or colonisation with pneumococci in the nasopharynx of children in this setting. The 10-valent pneumococcal conjugate vaccine (PCV10) was introduced into the routine infant immunisation schedule in Nepal in 2015. We aimed to investigate the effect of the introduction of PCV10 on pneumococcal carriage and disease in children in Nepal. Methods: We did an observational cohort study in children in Nepal. The hospital surveillance study took place in Patan Hospital, Kathmandu, and community studies in healthy children took place in Kathmandu and Okhaldhunga district. For the surveillance study, all children admitted to Patan Hospital between March 20, 2014, and Dec 31, 2019, aged between 2 months and 14 years with clinician-suspected pneumonia, were eligible for enrolment. For the community study, healthy children aged 0–8 weeks, 6–23 months, and 24–59 months were recruited from Kathmandu, and healthy children aged 6–23 months were recruited from Okhaldhunga. We assessed the programmatic effect of PCV10 introduction using surveillance for nasopharyngeal colonisation, pneumonia, and invasive bacterial disease from 1·5 years before vaccine introduction and 4·5 years after vaccine introduction. For the surveillance study, nasopharyngeal swabs, blood cultures, and chest radiographs were obtained from children admitted to Patan Hospital with suspected pneumonia or invasive bacterial disease. For the community study, nasopharyngeal swabs were obtained from healthy children in the urban and rural settings. Pneumonia outcomes were analysed using log-binomial models and adjusted prevalence ratios (aPR) comparing each calendar year after the introduction of the vaccine into the national programme with the pre-vaccine period (2014–15), adjusted for calendar month, age, and sex. Findings: Between March 20, 2014, and Dec 31, 2019, we enrolled 2051 children with suspected pneumonia, and 11 354 healthy children (8483 children aged 6–23 months, 761 aged 24–59 months, and 2110 aged 0–8 weeks) to assess nasopharyngeal colonisation. Among clinical pneumonia cases younger than 2 years, vaccine serotype carriage declined 82% (aPR 0·18 [95% CI 0·07–0·50]) by 2019. There was no decrease in vaccine serotype carriage in cases among older unvaccinated age groups. Carriage of the additional serotypes in PCV13 was 2·2 times higher by 2019 (aPR 2·17 [95% CI 1·16–4·05]), due to increases in serotypes 19A and 3. Vaccine serotype carriage in healthy children declined by 75% in those aged 6–23 months (aPR 0·25 [95% CI 0·19–0·33]) but not in those aged 24–59 months (aPR 0·59 [0·29–1·19]). A decrease in overall vaccine serotype carriage of 61% by 2019 (aPR 0·39 [95% CI 0·18–0·85]) was also observed in children younger than 8 weeks who were not yet immunised. Carriage of the additional PCV13 serotypes in children aged 6–23 months increased after PCV10 introduction for serotype 3 and 19A, but not for serotype 6A. The proportion of clinical pneumonia cases with endpoint consolidation on chest radiographs declined from 41% in the pre-vaccine period to 25% by 2018, but rose again in 2019 to 36%. Interpretation: The introduction of the PCV10 vaccine into the routine immunisation programme in Nepal has reduced vaccine serotype carriage in both healthy children and children younger than 2 years with pneumonia. Increases in serotypes 19A and 3 highlight the importance of continued surveillance to monitor the effect of vaccine programmes. This analysis demonstrates a robust approach to assessing vaccine effect in situations in which pneumococcal disease endpoint effectiveness studies are not possible. Funding: Gavi, the Vaccine Alliance and the World Health Organization.

Abstract Neisseria meningitidis is a major cause of meningitis and septicaemia. A MenB vaccine (4CMenB) was licensed by the European Medicines Agency in January 2013. Here we describe the blood transcriptome and proteome following infant immunisations with or without concomitant 4CMenB, to gain insight into the molecular mechanisms underlying post‐vaccination reactogenicity and immunogenicity. Infants were randomised to receive control immunisations (PCV13 and DTaP‐IPV‐Hib) with or without 4CMenB at 2 and 4 months of age. Blood gene expression and plasma proteins were measured prior to, then 4 h, 24 h, 3 days or 7 days post‐vaccination. 4CMenB vaccination was associated with increased expression of ENTPD7 and increased concentrations of 4 plasma proteins: CRP, G‐CSF, IL‐1RA and IL‐6. Post‐vaccination fever was associated with increased expression of SELL, involved in neutrophil recruitment. A murine model dissecting the vaccine components found the concomitant regimen to be associated with increased gene perturbation compared with 4CMenB vaccine alone with enhancement of pathways such as interleukin‐3, ‐5 and GM‐CSF signalling. Finally, we present transcriptomic profiles predictive of immunological and febrile responses following 4CMenB vaccine.

Summary: Background: Enteric fever is a serious public health concern in many low-income and middle-income countries. Numerous data gaps exist concerning the epidemiology of Salmonella enterica serotype Typhi (S Typhi) and Salmonella enterica serotype Paratyphi (S Paratyphi), which are the causative agents of enteric fever. We aimed to determine the burden of enteric fever in three urban sites in Africa and Asia. Methods: In this multicentre population-based study, we did a demographic census at three urban sites in Africa (Blantyre, Malawi) and Asia (Kathmandu, Nepal and Dhaka, Bangladesh) between June 1, 2016, and Sept 25, 2018. Households were selected randomly from the demographic census. Participants from within the geographical census area presenting to study health-care facilities were approached for recruitment if they had a history of fever for 72 h or more (later changed to >48 h) or temperature of 38·0°C or higher. Facility-based passive surveillance was done between Nov 11, 2016, and Dec 31, 2018, with blood-culture collection for febrile illness. We also did a community-based serological survey to obtain data on Vi-antibody defined infections. We calculated crude incidence for blood-culture-confirmed S Typhi and S Paratyphi infection, and calculated adjusted incidence and seroincidence of S Typhi blood-culture-confirmed infection. Findings: 423 618 individuals were included in the demographic census, contributing 626 219 person-years of observation for febrile illness surveillance. 624 S Typhi and 108 S Paratyphi A isolates were collected from the blood of 12 082 febrile patients. Multidrug resistance was observed in 44% S Typhi isolates and fluoroquinolone resistance in 61% of S Typhi isolates. In Blantyre, the overall crude incidence of blood-culture confirmed S Typhi was 58 cases per 100 000 person-years of observation (95% CI 48–70); the adjusted incidence was 444 cases per 100 000 person-years of observation (95% credible interval [CrI] 347–717). The corresponding rates were 74 (95% CI 62–87) and 1062 (95% CrI 683–1839) in Kathmandu, and 161 (95% CI 145–179) and 1135 (95% CrI 898–1480) in Dhaka. S Paratyphi was not found in Blantyre; overall crude incidence of blood-culture-confirmed S Paratyphi A infection was 6 cases per 100 000 person-years of observation (95% CI 3–11) in Kathmandu and 42 (95% CI 34–52) in Dhaka. Seroconversion rates for S Typhi infection per 100 000 person-years estimated from anti-Vi seroconversion episodes in serological surveillance were 2505 episodes (95% CI 1605–3727) in Blantyre, 7631 (95% CI 5913–9691) in Kathmandu, and 3256 (95% CI 2432–4270) in Dhaka. Interpretation: High disease incidence and rates of antimicrobial resistance were observed across three different transmission settings and thus necessitate multiple intervention strategies to achieve global control of these pathogens. Funding: Wellcome Trust and the Bill & Melinda Gates Foundation.

Summary: Background: Typhoid fever is a major public health problem in low-resource settings. Vaccination can help curb the disease and might reduce transmission. We have previously reported an interim analysis of the efficacy of typhoid conjugate vaccine (TCV) in Nepali children. Here we report the final results after 2 years of follow-up. Methods: We did a participant-masked and observer-masked individually randomised trial in Lalitpur, Nepal, in which 20 019 children aged 9 months to younger than 16 years were randomly assigned in a 1:1 ratio to receive a single dose of TCV (Typbar TCV, Bharat Biotech International, India) or capsular group A meningococcal conjugate vaccine (MenA). Participants were followed up until April 9, 2020. The primary outcome was blood culture-confirmed typhoid fever. Cases were captured via passive surveillance and active telephone surveillance followed by medical record review. The trial is registered at ISRCTN registry, ISRCTN43385161 and is ongoing. Findings: From Nov 20, 2017, to April 9, 2018, of 20 119 children screened, 20 019 participants were randomly assigned to receive TCV or MenA vaccine. There were 75 cases of blood culture-confirmed typhoid fever included in the analysis (13 in the TCV group and 62 in the MenA group) over the 2-year period. The protective efficacy of TCV against blood culture-confirmed typhoid fever at 2 years was 79·0% (95% CI 61·9–88·5; p

Background Vaccine nationalism has become a key topic of discussion during the development, testing, and rollout of COVID-19 vaccines. Media attention has highlighted the ways that global, coordinated access to vaccines has been limited during the pandemic. It has also exposed how some countries have secured vaccine supply, through bilateral purchase agreements and the way pharmaceutical companies have priced, negotiated, and delivered these supplies. Much of the focus of this debate has been on the vaccine supply ‘winners’ and ‘losers’, but the voices of public opinion have been more limited.Methods We explore the concepts of vaccine nationalism and internationalism from the perspective of vaccine trial participants, using an empirical perspectives study that involved interviews with phase I/II COVID-19 vaccine trial participants in Oxford, UK. We surveyed and interviewed participants between September and October 2020 about their views, motivations and experiences in taking part in the trial.Results First, we show how trial participants describe national and international ideas about vaccination as intertwined and challenge claims that these positions are mutually exclusive or oppositional. Second, we analyse these viewpoints further to show that vaccine nationalism is closely connected with national pride and metaphors of a country’s scientific achievements. Participants held a global outlook and were highly supportive of the prioritisation of vaccines by global need, but many were also pessimistic that such a solution could be possible.Conclusion Trial participants constitute an informed public group, with situated public expertise that the global community could draw on as an expert opinion. We argue that vaccine nationalism is strongly attached to national character and, therefore, it is more difficult for ownership of a vaccine to be thought of as international.

Summary: Background: Streptococcus pyogenes is a leading cause of infection-related morbidity and mortality. A reinvigorated vaccine development effort calls for new clinically relevant human S pyogenes experimental infection models to support proof of concept evaluation of candidate vaccines. We describe the initial Controlled Human Infection for Vaccination Against S pyogenes (CHIVAS-M75) study, in which we aimed to identify a dose of emm75 S pyogenes that causes acute pharyngitis in at least 60% of volunteers when applied to the pharynx by swab. Methods: This observational, dose-finding study was done in a clinical trials facility in Melbourne (VIC, Australia). Groups of healthy volunteers aged 18–40 years, at low risk of complicated S pyogenes disease, and without high type-specific anti-emm75 IgG antibodies against the challenge strain were challenged and closely monitored as inpatients for up to 6 days, and then as outpatients for 6 months. Antibiotics were started upon diagnosis (clinical signs and symptoms of pharyngitis and a positive rapid molecular test) or after 5 days in those without pharyngitis. Rapid test results were confirmed by standard bacterial culture. After a sentinel participant, cohorts of five and then ten participants were challenged, with protocol-directed dose-escalation or de-escalation for subsequent cohorts. The primary outcome was the proportion of participants at each dose level with pharyngitis by day 5 after challenge. The study is registered with ClinicalTrials.gov, NCT03361163. Findings: Between July 10, 2018, and Sept 23, 2019, 25 healthy adults were challenged with emm75 S pyogenes and included in analyses. Pharyngitis was diagnosed in 17 (85%; 95% CI 62–97) of 20 participants at the starting dose level (1–3 × 105 colony-forming units [CFU]/mL). This high proportion prompted dose de-escalation. At the lower dose level (1–3 × 104 CFU/mL), pharyngitis was diagnosed in one of five participants. Immunological, biochemical, and microbiological results supported the clinical picture, with acute symptomatic pharyngitis characterised by pharyngeal colonisation by S pyogenes accompanied by significantly elevated C-reactive protein and inflammatory cytokines (eg, interferon-γ and interleukin-6), and modest serological responses to streptolysin O and deoxyribonuclease B. There were no severe (grade 3) or serious adverse events related to challenge. Interpretation: We have established a reliable pharyngitis human infection model with reassuring early safety findings to accelerate development of vaccines and other interventions to control disease due to S pyogenes. Funding: Australian National Health and Medical Research Council.

Summary: Background: The effectiveness of the COVID-19 vaccination programme depends on mass participation: the greater the number of people vaccinated, the less risk to the population. Concise, persuasive messaging is crucial, particularly given substantial levels of vaccine hesitancy in the UK. Our aim was to test which types of written information about COVID-19 vaccination, in addition to a statement of efficacy and safety, might increase vaccine acceptance. Methods: For this single-blind, parallel-group, randomised controlled trial, we aimed to recruit 15 000 adults in the UK, who were quota sampled to be representative. Participants were randomly assigned equally across ten information conditions stratified by level of vaccine acceptance (willing, doubtful, or strongly hesitant). The control information condition comprised the safety and effectiveness statement taken from the UK National Health Service website; the remaining conditions addressed collective benefit, personal benefit, seriousness of the pandemic, and safety concerns. After online provision of vaccination information, participants completed the Oxford COVID-19 Vaccine Hesitancy Scale (outcome measure; score range 7–35) and the Oxford Vaccine Confidence and Complacency Scale (mediation measure). The primary outcome was willingness to be vaccinated. Participants were analysed in the groups they were allocated. p values were adjusted for multiple comparisons. The study was registered with ISRCTN, ISRCTN37254291. Findings: From Jan 19 to Feb 5, 2021, 15 014 adults were recruited. Vaccine hesitancy had reduced from 26·9% the previous year to 16·9%, so recruitment was extended to Feb 18 to recruit 3841 additional vaccine-hesitant adults. 12 463 (66·1%) participants were classified as willing, 2932 (15·6%) as doubtful, and 3460 (18·4%) as strongly hesitant (ie, report that they will avoid being vaccinated for as long as possible or will never get vaccinated). Information conditions did not alter COVID-19 vaccine hesitancy in those willing or doubtful (adjusted p values >0·70). In those strongly hesitant, COVID-19 vaccine hesitancy was reduced, in comparison to the control condition, by personal benefit information (mean difference –1·49, 95% CI –2·16 to –0·82; adjusted p=0·0015), directly addressing safety concerns about speed of development (−0·91, –1·58 to –0·23; adjusted p=0·0261), and a combination of all information (−0·86, –1·53 to –0·18; adjusted p=0·0313). In those strongly hesitant, provision of personal benefit information reduced hesitancy to a greater extent than provision of information on the collective benefit of not personally getting ill (−0·97, 95% CI –1·64 to –0·30; adjusted p=0·0165) or the collective benefit of not transmitting the virus (−1·01, –1·68 to –0·35; adjusted p=0·0150). Ethnicity and gender were found to moderate information condition outcomes. Interpretation: In the approximately 10% of the population who are strongly hesitant about COVID-19 vaccines, provision of information on personal benefit reduces hesitancy to a greater extent than information on collective benefits. Where perception of risk from vaccines is most salient, decision making becomes centred on the personal. As such, messaging that stresses the counterbalancing personal benefits is likely to prove most effective. The messaging from this study could be used in public health communications. Going forwards, the study highlights the need for future health campaigns to engage with the public on the terrain that is most salient to them. Funding: National Institute for Health Research (NIHR) Oxford Biomedical Research Centre and NIHR Oxford Health Biomedical Research Centre.

Abstract Misdiagnosis of enteric fever is a major global health problem, resulting in patient mismanagement, antimicrobial misuse and inaccurate disease burden estimates. Applying a machine learning algorithm to host gene expression profiles, we identified a diagnostic signature, which could distinguish culture‐confirmed enteric fever cases from other febrile illnesses (area under receiver operating characteristic curve > 95%). Applying this signature to a culture‐negative suspected enteric fever cohort in Nepal identified a further 12.6% as likely true cases. Our analysis highlights the power of data‐driven approaches to identify host response patterns for the diagnosis of febrile illnesses. Expression signatures were validated using qPCR, highlighting their utility as PCR‐based diagnostics for use in endemic settings.

Enteric fever is a systemic infection caused by Salmonella Typhi or Paratyphi A. In many endemic areas, these serovars co-circulate and can cause multiple infection-episodes in childhood. Prior exposure is thought to confer partial, but incomplete, protection against subsequent attacks of enteric fever. Empirical data to support this hypothesis are limited, and there are few studies describing the occurrence of heterologous-protection between these closely related serovars. We performed a challenge-re-challenge study using a controlled human infection model (CHIM) to investigate the extent of infection-derived immunity to Salmonella Typhi or Paratyphi A infection. We recruited healthy volunteers into two groups: naïve volunteers with no prior exposure to Salmonella Typhi/Paratyphi A and volunteers previously-exposed to Salmonella Typhi or Paratyphi A in earlier CHIM studies. Within each group, participants were randomised 1:1 to oral challenge with either Salmonella Typhi (104 CFU) or Paratyphi A (103 CFU). The primary objective was to compare the attack rate between naïve and previously challenged individuals, defined as the proportion of participants per group meeting the diagnostic criteria of temperature of ≥38°C persisting for ≥12 hours and/or S. Typhi/Paratyphi bacteraemia up to day 14 post challenge. The attack-rate in participants who underwent homologous re-challenge with Salmonella Typhi was reduced compared with challenged naïve controls, although this reduction was not statistically significant (12/27[44%] vs. 12/19[63%]; Relative risk 0.70; 95% CI 0.41-1.21; p = 0.24). Homologous re-challenge with Salmonella Paratyphi A also resulted in a lower attack-rate than was seen in challenged naïve controls (3/12[25%] vs. 10/18[56%]; RR0.45; 95% CI 0.16-1.30; p = 0.14). Evidence of protection was supported by a post hoc analysis in which previous exposure was associated with an approximately 36% and 57% reduced risk of typhoid or paratyphoid disease respectively on re-challenge. Individuals who did not develop enteric fever on primary exposure were significantly more likely to be protected on re-challenge, compared with individuals who developed disease on primary exposure. Heterologous re-challenge with Salmonella Typhi or Salmonella Paratyphi A was not associated with a reduced attack rate following challenge. Within the context of the model, prior exposure was not associated with reduced disease severity, altered microbiological profile or boosting of humoral immune responses. We conclude that prior Salmonella Typhi and Paratyphi A exposure may confer partial but incomplete protection against subsequent infection, but with a comparable clinical and microbiological phenotype. There is no demonstrable cross-protection between these serovars, consistent with the co-circulation of Salmonella Typhi and Paratyphi A. Collectively, these data are consistent with surveillance and modelling studies that indicate multiple infections can occur in high transmission settings, supporting the need for vaccines to reduce the burden of disease in childhood and achieve disease control. Trial registration NCT02192008; clinicaltrials.gov.

BackgroundIn surveillance for typhoid fever, under-detection of cases occurs when patients with fever do not seek medical care, or seek medical care but do not receive a blood test. Missing data may result in incorrect estimates of disease incidence.MethodsWe used data from an ongoing randomised clinical trial of typhoid conjugate vaccine among children in Nepal to determine if eligible patients attending our fever clinics who did not have blood taken for culture had a lower risk of disease than those who had blood drawn. We assessed clinical and demographic predictors of having blood taken for culture, and predictors of culture-positive results. Missing blood culture data were imputed using multiple imputations.ResultsDuring the first year of surveillance, 2392 fever presentations were recorded and 1615 (68%) of these had blood cultures. Children were more likely to have blood taken for culture if they were older, had fever for longer, a current temperature ≥38 degrees, or if typhoid or a urinary tract infection were suspected. Based on imputation models, those with blood cultures were 1.87 times more likely to have blood culture-positive fever than those with missing data.ConclusionClinical opinion on the cause of the fever may play a large part in the decision to offer blood culture, regardless of study protocol. Crude typhoid incidence estimates should be adjusted for the proportion of cases that go undetected due to missing blood cultures while adjusting for the lower likelihood of culture-positivity in the group with missing data.

Abstract Objective There are no vaccines for most of the major invasive Salmonella strains causing severe infection in humans. We evaluated the specificity of adaptive T memory cell responses generated after Salmonella Typhi exposure in humans against other major invasive Salmonella strains sharing capacity for dissemination. Methods T memory cells from eleven volunteers who underwent controlled oral challenge with wt S. Typhi were characterised by flow cytometry for cross‐reactive cellular cytokine/chemokine effector responses or evidence of degranulation upon stimulation with autologous B‐lymphoblastoid cells infected with either S. Typhi, Salmonella Paratyphi A (PA), S. Paratyphi B (PB) or an invasive nontyphoidal Salmonella strain of the S. Typhimurium serovar (iNTSTy). Results Blood T‐cell effector memory (TEM) responses after exposure to S. Typhi in humans evolve late, peaking weeks after infection in most volunteers. Induced multifunctional CD4+ Th1 and CD8+ TEM cells elicited after S. Typhi challenge were cross‐reactive with PA, PB and iNTSTy. The magnitude of multifunctional CD4+ TEM cell responses to S. Typhi correlated with induction of cross‐reactive multifunctional CD8+ TEM cells against PA, PB and iNTSTy. Highly multifunctional subsets and T central memory and T effector memory cells that re‐express CD45 (TEMRA) demonstrated less heterologous T‐cell cross‐reactivity, and multifunctional Th17 elicited after S. Typhi challenge was not cross‐reactive against other invasive Salmonella. Conclusion Gaps in cross‐reactive immune effector functions in human T‐cell memory compartments were highly dependent on invasive Salmonella strain, underscoring the importance of strain‐dependent vaccination in the design of T‐cell‐based vaccines for invasive Salmonella.

BackgroundThe treatment of enteric fever is complicated by the emergence of antimicrobial resistant Salmonella Typhi. Azithromycin is commonly used for first-line treatment of uncomplicated enteric fever, but the response to treatment may be sub-optimal in some patient groups when compared with fluoroquinolones.MethodsWe performed an analysis of responses to treatment with azithromycin (500mg once-daily, 14 days) or ciprofloxacin (500mg twice-daily, 14 days) in healthy UK volunteers (18-60 years) enrolled into two Salmonella controlled human infection studies. Study A was a single-centre, open-label, randomised trial. Participants were randomised 1:1 to receive open-label oral ciprofloxacin or azithromycin, stratified by vaccine group (Vi-polysaccharide, Vi-conjugate or control Men-ACWY vaccine). Study B was an observational challenge/re-challenge study, where participants were randomised to challenge with Salmonella Typhi or Salmonella Paratyphi A. Outcome measures included fever clearance time, blood-culture clearance time and a composite measure of prolonged treatment response (persistent fever ≥38.0°C for ≥72 hours, persistently positive S. Typhi blood cultures for ≥72 hours, or change in antibiotic treatment). Both trials are registered with ClinicalTrials.gov (NCT02324751 and NCT02192008).FindingsIn 81 participants diagnosed with S. Typhi in two studies, treatment with azithromycin was associated with prolonged bacteraemia (median 90.8 hours [95% CI: 65.9-93.8] vs. 20.1 hours [95% CI: 7.8-24.3], pInterpretationAzithromycin at a dose of 500mg daily is an effective treatment for fully sensitive strains of S. Typhi but is associated with delayed treatment response and prolonged bacteraemia when compared with ciprofloxacin within the context of a human challenge model. Whilst the cellular accumulation of azithromycin is predicted to be sufficient to treat intracellular S. Typhi, systemic exposure may be sub-optimal for the elimination of extracellular circulating S. Typhi. In an era of increasing antimicrobial resistance, further studies are required to define appropriate azithromycin dosing regimens for enteric fever and to assess novel treatment strategies, including combination therapies.Trial registrationClinicalTrials.gov (NCT02324751 and NCT02192008).

BackgroundEncephalitis, characterised as inflammation of the brain tissue, is an important cause of acquired brain injury in children. Objective clinical outcomes vary significantly between affected patients, however they do not always correlate with quality of life as reported by parents. The aim of this study was to explore how parents experience and interpret outcomes in relation to their child who has been affected by encephalitis.MethodsData were derived from in-depth, semi-structured interviews, with 15 parents of 12 children and young people affected by encephalitis. Paediatric cases were identified from the retrospective arm of the research programme 'ENCEPH-UK-Understanding and Improving the Outcome of Encephalitis', and from the prospective UK childhood meningitis and encephalitis cohort study (UK-ChiMES, 2012 to 2016). Data were analysed thematically.ResultsParents' perspectives on important outcomes for their child and family changed during the different stages of the encephalitis illness trajectory: from acute illness, recovery and rehabilitation, then reintegration into everyday life. Parents' understanding of their children's overall outcome was informed by their own experiences, involving comparisons with other children and reflections on their child's problems before, during and after the acute illness.ConclusionOutcomes in paediatric encephalitis need to be understood in terms of the context of the patient and family experience as well as the timeframe of recovery. The research highlights the need to include more patient, parent and/or carer reported outcome measures during patient assessment, and that assessment should be repeated during recovery as family concerns change. In the longer term, these parameters could be included in clinical and rehabilitation practice to further support child recovery.

Streptococcus pneumoniae serotype 3 remains a significant cause of morbidity and mortality worldwide, despite inclusion in the 13-valent pneumococcal conjugate vaccine (PCV13). Serotype 3 increased in carriage since the implementation of PCV13 in the USA, while invasive disease rates remain unchanged. We investigated the persistence of serotype 3 in carriage and disease, through genomic analyses of a global sample of 301 serotype 3 isolates of the Netherlands3-31 (PMEN31) clone CC180, combined with associated patient data and PCV utilization among countries of isolate collection. We assessed phenotypic variation between dominant clades in capsule charge (zeta potential), capsular polysaccharide shedding, and susceptibility to opsonophagocytic killing, which have previously been associated with carriage duration, invasiveness, and vaccine escape. We identified a recent shift in the CC180 population attributed to a lineage termed Clade II, which was estimated by Bayesian coalescent analysis to have first appeared in 1968 [95% HPD: 1939-1989] and increased in prevalence and effective population size thereafter. Clade II isolates are divergent from the pre-PCV13 serotype 3 population in non-capsular antigenic composition, competence, and antibiotic susceptibility, the last of which resulting from the acquisition of a Tn916-like conjugative transposon. Differences in recombination rates among clades correlated with variations in the ATP-binding subunit of Clp protease, as well as amino acid substitutions in the comCDE operon. Opsonophagocytic killing assays elucidated the low observed efficacy of PCV13 against serotype 3. Variation in PCV13 use among sampled countries was not independently correlated with the CC180 population shift; therefore, genotypic and phenotypic differences in protein antigens and, in particular, antibiotic resistance may have contributed to the increase of Clade II. Our analysis emphasizes the need for routine, representative sampling of isolates from disperse geographic regions, including historically under-sampled areas. We also highlight the value of genomics in resolving antigenic and epidemiological variations within a serotype, which may have implications for future vaccine development.

BACKGROUND:The temporal and spatial change in trends of antimicrobial resistance (AMR) in typhoid have not been systematically studied, and such information will be critical for defining intervention, as well as planning sustainable prevention strategies. METHODOLOGY AND FINDINGS:To identify the phenotypic trends in AMR, 13,833 individual S. Typhi isolates, reported from 1973 to 2018 in 62 publications, were analysed to determine the AMR preponderance over time. Separate analyses of molecular resistance determinants present in over 4,000 isolates reported in 61 publications were also conducted. Multi-drug resistant (MDR) typhoid is in decline in Asia in a setting of high fluoroquinolone resistance while it is on the increase in Africa. Mutations in QRDRs in gyrA (S83F, D87N) and parC (S80I) are the most common mechanisms responsible for fluoroquinolone resistance. Cephalosporin resistant S. Typhi, dubbed extensively drug-resistant (XDR) is a real threat and underscores the urgency in deploying the Vi-conjugate vaccines. CONCLUSION:From these observations, it appears that AMR in S. Typhi will continue to emerge leading to treatment failure, changes in antimicrobial policy and further resistance developing in S. Typhi isolates and other Gram-negative bacteria in endemic regions. The deployment of typhoid conjugate vaccines to control the disease in endemic regions may be the best defence.

Children are substantially affected by enteric fever in most settings with a high burden of the disease, including Nepal. However pathogen population structure and transmission dynamics are poorly delineated in young children, the proposed target group for immunization programs. Here we present whole genome sequencing and antimicrobial susceptibility data on 198 S. Typhi and 66 S. Paratyphi A isolated from children aged 2 months to 15 years of age during blood culture surveillance at Patan Hospital, Nepal, 2008-2016.S. Typhi was the dominant agent and comprised several distinct genotypes, dominated by 4.3.1 (H58). The heterogeneity of genotypes in children under five was reduced compared to data from 2005-2006, attributable to ongoing clonal expansion of H58. Most isolates (86%) were non-susceptible to fluoroquinolones, associated mainly with S. Typhi H58 lineage II and S. Paratyphi A harbouring mutations in the quinolone resistance-determining region (QRDR); non-susceptible strains from these groups accounted for 50% and 25% of all isolates. Multi-drug resistance (MDR) was rare (3.5% of S. Typhi, 0 S. Paratyphi A) and restricted to chromosomal insertions of resistance genes in H58 lineage I strains. Temporal analyses revealed a shift in dominance from H58 Lineage I to H58 Lineage II, with the latter being significantly more common after 2010. Comparison to global data sets showed the local S. Typhi and S. Paratyphi A strains had close genetic relatives in other South Asian countries, indicating regional strain circulation. Multiple imports from India of ciprofloxacin-resistant H58 lineage II strains were identified, but these were rare and showed no evidence of clonal replacement of local S. Typhi.These data indicate that enteric fever in Nepal continues to be a major public health issue with ongoing inter- and intra-country transmission, and highlights the need for regional coordination of intervention strategies. The absence of a S. Paratyphi A vaccine is cause for concern, given its prevalence as a fluoroquinolone resistant enteric fever agent in this setting.

In the development of new vaccines, understanding the level of vaccine-induced antibody that is sufficient to protect against disease can simplify and expedite the development and licensing process. If there is an accepted threshold antibody level that is indicative of protection, then smaller trials measuring antibody concentration alone can be conducted to test new vaccines, instead of large efficacy studies powered on clinical outcomes. Commonly, threshold levels of protective antibody are determined from clinical efficacy trials in which clinical endpoints are measured on everyone and a small subset of participants have antibody concentrations measured. The proportion of participants with antibody below a threshold in each group in the immunogenicity subset can be compared to the proportions with disease in each group in the larger trial to find an appropriate threshold. Mathematically, this method seeks to compute an absolute threshold whereby antibody above the threshold provides complete, sterilizing immunity. However, in practice it is often understood that such thresholds may only be indicative of a relative degree of protection rather than an absolute one. Although this approach is common, the accuracy of such methods when the underlying mathematical assumptions do not hold true, has never been tested. We simulated data from clinical trial scenarios under varying assumptions of vaccine efficacy and calculated antibody thresholds of protection. We estimated the bias in the calculated thresholds derived from each scenario and showed that in many situations this method produces inflated estimates of thresholds, particularly if a vaccine induces high levels of antibody or when the underlying assumption of sterilizing immunity is violated.

Many vaccines contain multiple components. Licensed pneumococcal conjugate vaccines (PCV) contain polysaccharides from 7, 10, or 13 different serotypes of Streptococcus pneumoniae. The main outcomes in randomised trials of pneumococcal vaccines are serotype-specific antibody measures. Comparisons are made between groups for each serotype, resulting in multiple separate comparisons of treatment effects which can be complicated to interpret. We investigated methods for computing the overall difference between vaccine groups across all serotypes.Pneumococcal antibody concentrations were obtained from a randomised controlled trial of ten-valent pneumococcal vaccine, conducted in Kathmandu, Nepal. Infants received either 2 priming doses of vaccine at 6 and 14 weeks of age followed by a booster (2+1), or 3 priming doses at 6, 10, and 14 weeks of age with no booster (3+0). The overall difference between vaccine schedules across all serotypes was computed at each visit using a multivariate linear model with equal weights for each serotype. Alternative weights were derived from invasive pneumococcal disease cases in Nepal, Bangladesh and Pakistan, and from estimates of the relative invasiveness of each serotype and used in sensitivity analyses.When 10 separate estimates of treatment differences were computed the ratio of antibody responses for each serotype in the 2+1 group compared with the 3+0 group at 10 months of age varied greatly, with serotype-specific GMRs ranging from 2.80 for serotype 14, to 9.14 for serotype 18C. Using equal weights for each serotype, the overall geometric mean ratio (GMR) was 5.02 (95% CI 4.06-6.22) at 10 months of age, and 1.46 (95% CI 1.14-1.88) at 3 years of age. Using weights based on disease incidence gave GMRs ranging from 5.15 to 6.63 at 10 months of age, and 1.47 to 1.78 at 3 years of age. Using weights based on relative invasiveness gave estimates of 6.81 and 1.59, at 10 months and 3 years respectively.PCV clinical trial data have a multivariate structure with correlated outcomes for different serotypes. When analysing each serotype separately, the multiple estimates of the treatment effect can complicate the interpretation of trial results. Reporting a single overall estimate which accounts for the correlation between outcomes can simplify such interpretation. Treatment effects can be weighted equally or alternative weights derived from independent data can be used. Many modern vaccines have multiple components, such as quadrivalent meningococcal group ACWY vaccine or four-component group B meningococcal vaccine, thus these methods are widely applicable.

Background: There is little current consensus regarding the route or duration of antibiotic treatment for acute osteomyelitis (OM) and septic arthritis (SA) in children. Objective: To assess the overall feasibility and inform the design of a future randomised controlled trial (RCT) to reduce the duration of intravenous (i.v.) antibiotic use in paediatric OM and SA. Design: (1) A prospective service evaluation (cohort study) to determine the current disease spectrum and UK clinical practice in paediatric OM/SA; (2) a prospective cohort substudy to assess the use of targeted polymerase chain reaction (PCR) in diagnosing paediatric OM/SA; (3) a qualitative study to explore families’ views and experiences of OM/SA; and (4) the development of a core outcome set via a systematic review of literature, Delphi clinician survey and stakeholder consensus meeting. Setting: Forty-four UK secondary and tertiary UK centres (service evaluation). Participants: Children with OM/SA. Interventions: PCR diagnostics were compared with culture as standard of care. Semistructured interviews were used in the qualitative study. Results: Data were obtained on 313 cases of OM/SA, of which 218 (61.2%) were defined as simple disease and 95 (26.7%) were defined as complex disease. The epidemiology of paediatric OM/SA in this study was consistent with existing European data. Children who met oral switch criteria less than 7 days from starting i.v. antibiotics were less likely to experience treatment failure (9.6%) than children who met oral switch criteria after 7 days of i.v. therapy (16.1% when switch was between 1 and 2 weeks; 18.2% when switch was > 2 weeks). In 24 out of 32 simple cases (75%) and 8 out of 12 complex cases (67%) in which the targeted PCR was used, a pathogen was detected. The qualitative study demonstrated the importance to parents and children of consideration of short- and long-term outcomes meaningful to families themselves. The consensus meeting agreed on the following outcomes: rehospitalisation or recurrence of symptoms while on oral antibiotics, recurrence of infection, disability at follow-up, symptom free at 1 year, limb shortening or deformity, chronic OM or arthritis, amputation or fasciotomy, death, need for paediatric intensive care, and line infection. Oral switch criteria were identified, including resolution of fever for ≥ 48 hours, tolerating oral food and medicines, and pain improvement. Limitations: Data were collected in a 6-month period, which might not have been representative, and follow-up data for long-term complications are limited. Conclusions: A future RCT would need to recruit from all tertiary and most secondary UK hospitals. Clinicians have implemented early oral switch for selected patients with simple disease without formal clinical trial evidence of safety. However, the current criteria by which decisions to make the oral switch are made are not clearly established or evidence based. Future work: A RCT in simple OM and SA comparing shorter- or longer-course i.v. therapy is feasible in children randomised after oral switch criteria are met after 7 days of i.v. therapy, excluding children meeting oral switch criteria in the first week of i.v. therapy. This study design meets clinician preferences and addresses parental concerns not to randomise prior to oral switch criteria being met. Funding: The National Institute for Health Research Health Technology Assessment programme.

Background: Vaccines and prophylactic antibodies against respiratory syncytial virus (RSV) are in development and likely to be available in the next 5–10 years. The most efficient way to use these products when they become available is an important consideration for public health decision makers. Methods: We performed a multivariate regression analysis to estimate the burden of RSV in children younger than 5 years in England (UK), a representative high-income temperate country, and used these results to assess the potential effect of different RSV immunisation strategies (targeting vaccination for infants, or pregnant women, or prophylactic antibodies for neonates). We did a cost-effectiveness analysis for these strategies, implemented either separately or concurrently, and assessed the effect of restricting vaccination to certain months of the year. Findings: We estimated that RSV is responsible for 12 primary care consultations (95% CI 11·9–12·1) and 0·9 admissions to hospital annually per 100 children younger than 5 years (95% CI 0·89–0·90), with the major burden occurring in infants younger than 6 months. The most cost-effective strategy was to selectively immunise all children born before the start of the RSV season (maximum price of £220 [95% uncertainty interval (UI) 208–232] per vaccine, for an incremental cost-effectiveness ratio of £20 000 per quality-adjusted life-year). The maximum price per fully protected person that should be paid for the infant, newborn, and maternal strategies without seasonal restrictions was £192 (95% UI 168–219), £81 (76–86), and £54 (51–57), respectively. Interpretation: Nearly double the number of primary care consultations, and nearly five times the number of admissions to hospital occurred with RSV compared with influenza. RSV vaccine and antibody strategies are likely to be cost-effective if they can be priced below around £200 per fully protected person. A seasonal vaccination strategy is likely to provide the most direct benefits. Herd effects might render a year-round infant vaccination strategy more appealing, although it is currently unclear whether such a programme would induce herd effects. Funding: UK National Institute for Health Research.

Powder-injectors use gas propulsion to deposit lyophilised drug or vaccine particles in the epidermal and sub epidermal layers of the skin. We prepared dry-powder (Tg = 45.2 ± 0.5°C) microparticles (58.1 μm) of a MenY-CRM197 glyconjugate vaccine (0.5% wt.) for intradermal needle-free powder injection (NFPI). SFD used ultrasound atomisation of the liquid vaccine-containing excipient feed, followed by lyophilisation above the glass transition temperature (Tg' = - 29.9 ± 0.3°C). This resulted in robust particles (density~ 0.53 ±0.09 g/cm3) with a narrow volume size distribution (mean diameter 58.1 μm, and span = 1.2), and an impact parameter (ρvr ~ 11.5 kg/m·s) sufficient to breach the Stratum corneum (sc). The trehalose, manitol, dextran (10 kDa), dextran (150 kDa) formulation, or TMDD (3:3:3:1), protected the MenY-CRM197 glyconjugate during SFD with minimal loss, no detectable chemical degradation or physical aggregation. In a capsular group Y Neisseria meningitidis serum bactericidal assay (SBA) with human serum complement, the needle free vaccine, which contained no alum adjuvant, induced functional protective antibody responses in vivo of similar magnitude to the conventional vaccine injected by hypodermic needle and syringe and containing alum adjuvant. These results demonstrate that needle-free vaccination is both technically and immunologically valid, and could be considered for vaccines in development.

BACKGROUND:Typhoid persists as a major cause of global morbidity. While several licensed vaccines to prevent typhoid are available, they are of only moderate efficacy and unsuitable for use in children less than two years of age. Development of new efficacious vaccines is complicated by the human host-restriction of Salmonella enterica serovar Typhi (S. Typhi) and lack of clear correlates of protection. In this study, we aimed to evaluate the protective efficacy of a single dose of the oral vaccine candidate, M01ZH09, in susceptible volunteers by direct typhoid challenge. METHODS AND FINDINGS:We performed a randomised, double-blind, placebo-controlled trial in healthy adult participants at a single centre in Oxford (UK). Participants were allocated to receive one dose of double-blinded M01ZH09 or placebo or 3-doses of open-label Ty21a. Twenty-eight days after vaccination, participants were challenged with 104CFU S. Typhi Quailes strain. The efficacy of M01ZH09 compared with placebo (primary outcome) was assessed as the percentage of participants reaching pre-defined endpoints constituting typhoid diagnosis (fever and/or bacteraemia) during the 14 days after challenge. Ninety-nine participants were randomised to receive M01ZH09 (n = 33), placebo (n = 33) or 3-doses of Ty21a (n = 33). After challenge, typhoid was diagnosed in 18/31 (58.1% [95% CI 39.1 to 75.5]) M01ZH09, 20/30 (66.7% [47.2 to 87.2]) placebo, and 13/30 (43.3% [25.5 to 62.6]) Ty21a vaccine recipients. Vaccine efficacy (VE) for one dose of M01ZH09 was 13% [95% CI -29 to 41] and 35% [-5 to 60] for 3-doses of Ty21a. Retrospective multivariable analyses demonstrated that pre-existing anti-Vi antibody significantly reduced susceptibility to infection after challenge; a 1 log increase in anti-Vi IgG resulting in a 71% decrease in the hazard ratio of typhoid diagnosis ([95% CI 30 to 88%], p = 0.006) during the 14 day challenge period. Limitations to the study included the requirement to limit the challenge period prior to treatment to 2 weeks, the intensity of the study procedures and the high challenge dose used resulting in a stringent model. CONCLUSIONS:Despite successfully demonstrating the use of a human challenge study to directly evaluate vaccine efficacy, a single-dose M01ZH09 failed to demonstrate significant protection after challenge with virulent Salmonella Typhi in this model. Anti-Vi antibody detected prior to vaccination played a major role in outcome after challenge. TRIAL REGISTRATION:ClinicalTrials.gov (NCT01405521) and EudraCT (number 2011-000381-35).

A novel human oral challenge model with wild-type Salmonella Typhi (S. Typhi) was recently established by the Oxford Vaccine Group. In this model, 104 CFU of Salmonella resulted in 65% of participants developing typhoid fever (referred here as typhoid diagnosis -TD-) 6-9 days post-challenge. TD was diagnosed in participants meeting clinical (oral temperature ≥38°C for ≥12h) and/or microbiological (S. Typhi bacteremia) endpoints. Changes in B cell subpopulations following S. Typhi challenge remain undefined. To address this issue, a subset of volunteers (6 TD and 4 who did not develop TD -NoTD-) was evaluated. Notable changes included reduction in the frequency of B cells (cells/ml) of TD volunteers during disease days and increase in plasmablasts (PB) during the recovery phase (>day 14). Additionally, a portion of PB of TD volunteers showed a significant increase in activation (CD40, CD21) and gut homing (integrin α4β7) molecules. Furthermore, all BM subsets of TD volunteers showed changes induced by S. Typhi infections such as a decrease in CD21 in switched memory (Sm) CD27+ and Sm CD27- cells as well as upregulation of CD40 in unswitched memory (Um) and Naïve cells. Furthermore, changes in the signaling profile of some BM subsets were identified after S. Typhi-LPS stimulation around time of disease. Notably, naïve cells of TD (compared to NoTD) volunteers showed a higher percentage of cells phosphorylating Akt suggesting enhanced survival of these cells. Interestingly, most these changes were temporally associated with disease onset. This is the first study to describe differences in B cell subsets directly related to clinical outcome following oral challenge with wild-type S. Typhi in humans.

BACKGROUND:Enteric fever remains an important cause of morbidity in many low-income countries and Salmonella Paratyphi A has emerged as the aetiological agent in an increasing proportion of cases. Lack of adequate diagnostics hinders early diagnosis and prompt treatment of both typhoid and paratyphoid but development of assays to identify paratyphoid has been particularly neglected. Here we describe the development of a rapid and sensitive blood culture PCR method for detection of Salmonella Paratyphi A from blood, potentially allowing for appropriate diagnosis and antimicrobial treatment to be initiated on the same day. METHODS:Venous blood samples from volunteers experimentally challenged orally with Salmonella Paratyphi A, who subsequently developed paratyphoid, were taken on the day of diagnosis; 10 ml for quantitative blood culture and automated blood culture, and 5 ml for blood culture PCR. In the latter assay, bacteria were grown in tryptone soy broth containing 2.4% ox bile and micrococcal nuclease for 5 hours (37°C) before bacterial DNA was isolated for PCR detection targeting the fliC-a gene of Salmonella Paratyphi A. RESULTS:An optimized broth containing 2.4% ox bile and micrococcal nuclease, as well as a PCR test was developed for a blood culture PCR assay of Salmonella Paratyphi A. The volunteers diagnosed with paratyphoid had a median bacterial burden of 1 (range 0.1-6.9) CFU/ml blood. All the blood culture PCR positive cases where a positive bacterial growth was shown by quantitative blood culture had a bacterial burden of ≥ 0.3 CFU/ ml blood. The blood culture PCR assay identified an equal number of positive cases as automated blood culture at higher bacterial loads (≥0.3 CFU/ml blood), but utilized only half the volume of specimens. CONCLUSIONS:The blood culture PCR method for detection of Salmonella Paratyphi A can be completed within 9 hours and offers the potential for same-day diagnosis of enteric fever. Using 5 ml blood, it exhibited a lower limit of detection equal to 0.3 CFU/ml blood, and it performed at least as well as automated blood culture at higher bacterial loads (≥0.3 CFU/ml blood) of clinical specimens despite using half the volume of blood. The findings warrant its further study in endemic populations with a potential use as a novel diagnostic which fills the present gap of paratyphoid diagnostics.

Opa proteins are major surface-expressed proteins located in the Neisseria meningitidis outer membrane, and are potential meningococcal vaccine candidates. Although Opa proteins elicit high levels of bactericidal antibodies following immunisation in mice, progress towards human clinical trials has been delayed due to previous findings that Opa inhibits T cell proliferation in some in vitro assays. However, results from previous studies are conflicting, with different Opa preparations and culture conditions being used. We investigated the effects of various Opa+ and Opa- antigens from N. meningitidis strain H44/76 in a range of in vitro conditions using peripheral blood mononuclear cells (PBMCs) and purified CD4+ T cells, measuring T cell proliferation by CFSE dilution using flow cytometry. Wild type recombinant and liposomal Opa proteins inhibited CD4+ T cell proliferation after stimulation with IL-2, anti-CD3 and anti-CD28, and these effects were reduced by mutation of the CEACAM1-binding region of Opa. These effects were not observed in culture with ex vivo PBMCs. Opa+ and Opa- OMVs did not consistently exert a stimulatory or inhibitory effect across different culture conditions. These data do not support a hypothesis that Opa proteins would be inhibitory to T cells if given as a vaccine component, and T cell immune responses to OMV vaccines are unlikely to be significantly affected by the presence of Opa proteins.

Neisseria meningitidis recruits host human complement inhibitors to its surface to down-regulate complement activation and enhance survival in blood. We have investigated whether such complement inhibitor binding occurs after vaccination with native outer membrane vesicles (nOMVs), and limits immunogenicity of such vaccines. To this end, nOMVs reactogenic lipopolysaccharide was detoxified by deletion of the lpxl1 gene (nOMVlpxl1). nOMVs unable to bind human complement factor H (hfH) were generated by additional deletions of the genes encoding factor H binding protein (fHbp) and neisserial surface protein A (NspA) (nOMVdis). Antibody responses elicited in mice with nOMVdis were compared to those elicited with nOMVlpxl1 in the presence of hfH. Results demonstrate that the administration of human fH to mice immunized with fHbp containing OMVlpxl1 decreased immunogenicity against fHbp (but not against the OMV as a whole). The majority of the OMV-induced bactericidal immune response (OMVlpxl1 or OMVdis) was versus PorA. Despite a considerable reduction of hfH binding to nOMVdis, and the absence of the vaccine antigen fHbp, immunogenicity in mice was not different from nOMVlpxl1, in the absence or presence of hfH (serum bactericidal titers of 1:64 vs 1:128 after one dose in the nOMVdis and nOMVlpxl1-immunized groups respectively). Therefore, partial inhibition of fH binding did not enhance immunity in this model.

Avian influenza continues to circulate and remains a global health threat not least because of the associated high mortality. In this study antibody persistence, booster vaccine response and cross-clade immune response between two influenza A(H5N1) vaccines were compared. Participants aged over 18-years who had previously been immunized with a clade 1, A/Vietnam vaccine were re-immunized at 6-months with 7.5 μg of the homologous strain or at 22-months with a clade 2, alum-adjuvanted, A/Indonesia vaccine. Blood sampled at 6, 15 and 22-months after the primary course was used to assess antibody persistence. Antibody concentrations 6-months after primary immunisation with either A/Vietnam vaccine 30 μg alum-adjuvanted vaccine or 7.5 μg dose vaccine were lower than 21-days after the primary course and waned further with time. Re-immunization with the clade 2, 30 μg alum-adjuvanted vaccine confirmed cross-clade reactogenicity. Antibody cross-reactivity between A(H5N1) clades suggests that in principle a prime-boost vaccination strategy may provide both early protection at the start of a pandemic and improved antibody responses to specific vaccination once available.ClinicalTrials.gov NCT00415129.

High-throughput sequencing of the B cell receptor (BCR) repertoire can provide rapid characterization of the B cell response in a wide variety of applications in health, after vaccination and in infectious, inflammatory and immune-driven disease, and is starting to yield clinical applications. However, the interpretation of repertoire data is compromised by a lack of studies to assess the intra and inter-individual variation in the BCR repertoire over time in healthy individuals. We applied a standardized isotype-specific BCR repertoire deep sequencing protocol to a single highly sampled participant, and then evaluated the method in 10 further participants to comprehensively describe such variation. We assessed total repertoire metrics of mutation, diversity, VJ gene usage and isotype subclass usage, as well as tracking specific BCR sequence clusters. There was good assay reproducibility (both in PCR amplification and biological replicates), but we detected striking fluctuations in the repertoire over time that we hypothesize may be due to subclinical immune activation. Repertoire properties were unique for each individual, which could partly be explained by a decrease in IgG2 with age, and genetic differences at the immunoglobulin locus. There was a small repertoire of public clusters (0.5, 0.3 and 1.4% of total IgA, IgG and IgM clusters respectively), which was enriched for expanded clusters containing sequences with suspected specificity towards antigens that should have been historically encountered by all participants through prior immunization or infection. We thus provide baseline BCR repertoire information that can be used to inform future study design, and aid in interpretation of results from these studies. Furthermore our results indicate that BCR repertoire studies could be used to track changes in the public repertoire in and between populations that might relate to population immunity against infectious diseases, and identify the characteristics of inflammatory and immunological diseases.

BACKGROUND:Iron is a key pathogenic determinant of many infectious diseases. Hepcidin, the hormone responsible for governing systemic iron homeostasis, is widely hypothesized to represent a key component of nutritional immunity through regulating the accessibility of iron to invading microorganisms during infection. However, the deployment of hepcidin in human bacterial infections remains poorly characterized. Typhoid fever is a globally significant, human-restricted bacterial infection, but understanding of its pathogenesis, especially during the critical early phases, likewise is poorly understood. Here, we investigate alterations in hepcidin and iron/inflammatory indices following experimental human typhoid challenge. METHODOLOGY/PRINCIPAL FINDINGS:Fifty study participants were challenged with Salmonella enterica serovar Typhi and monitored for evidence of typhoid fever. Serum hepcidin, ferritin, serum iron parameters, C-reactive protein (CRP), and plasma IL-6 and TNF-alpha concentrations were measured during the 14 days following challenge. We found that hepcidin concentrations were markedly higher during acute typhoid infection than at baseline. Hepcidin elevations mirrored the kinetics of fever, and were accompanied by profound hypoferremia, increased CRP and ferritin, despite only modest elevations in IL-6 and TNF-alpha in some individuals. During inflammation, the extent of hepcidin upregulation associated with the degree of hypoferremia. CONCLUSIONS/SIGNIFICANCE:We demonstrate that strong hepcidin upregulation and hypoferremia, coincident with fever and systemic inflammation, are hallmarks of the early innate response to acute typhoid infection. We hypothesize that hepcidin-mediated iron redistribution into macrophages may contribute to S. Typhi pathogenesis by increasing iron availability for macrophage-tropic bacteria, and that targeting macrophage iron retention may represent a strategy for limiting infections with macrophage-tropic pathogens such as S. Typhi.

A new human oral challenge model with wild-type Salmonella Typhi (S. Typhi) was recently developed. In this model, ingestion of 104 CFU of Salmonella resulted in 65% of subjects developing typhoid fever (referred here as typhoid diagnosis -TD-) 5-10 days post-challenge. TD criteria included meeting clinical (oral temperature ≥38°C for ≥12 h) and/or microbiological (S. Typhi bacteremia) endpoints. One of the first lines of defense against pathogens are the cells of the innate immune system (e.g., monocytes, dendritic cells -DCs-). Various changes in circulating monocytes and DCs have been described in the murine S. Typhimurium model; however, whether similar changes are present in humans remains to be explored. To address these questions, a subset of volunteers (5 TD and 3 who did not develop typhoid despite oral challenge -NoTD-) were evaluated for changes in circulating monocytes and DCs. Expression of CD38 and CD40 were upregulated in monocytes and DCs in TD volunteers during the disease days (TD-0h to TD-96h). Moreover, integrin α4β7, a gut homing molecule, was upregulated on monocytes but not DCs. CD21 upregulation was only identified in DCs. These changes were not observed among NoTD volunteers despite the same oral challenge. Moreover, monocytes and DCs from NoTD volunteers showed increased binding to S. Typhi one day after challenge. These monocytes showed phosphorylation of p38MAPK, NFkB and Erk1/2 upon stimulation with S. Typhi-LPS-QDot micelles. In contrast, monocytes from TD volunteers showed only a moderate increase in S. Typhi binding 48 h and 96 h post-TD, and only Erk1/2 phosphorylation. This is the first study to describe different activation and migration profiles, as well as differential signaling patterns, in monocytes and DCs which relate directly to the clinical outcome following oral challenge with wild type S. Typhi.

Salmonella Typhi (S. Typhi), the causative agent of typhoid fever, causes significant morbidity and mortality worldwide. Currently available vaccines are moderately efficacious, and identification of immunological responses associated with protection or disease will facilitate the development of improved vaccines. We investigated S. Typhi-specific modulation of activation and homing potential of circulating regulatory T cells (Treg) by flow and mass cytometry using specimens obtained from a human challenge study. Peripheral blood mononuclear cells were obtained from volunteers pre- and at multiple time-points post-challenge with wild-type S. Typhi. We identified differing patterns of S. Typhi-specific modulation of the homing potential of circulating Treg between volunteers diagnosed with typhoid (TD) and those who were not (No TD). TD volunteers demonstrated up-regulation of the gut homing molecule integrin α4ß7 pre-challenge, followed by a significant down-regulation post-challenge consistent with Treg homing to the gut. Additionally, S. Typhi-specific Treg from TD volunteers exhibited up-regulation of activation molecules post-challenge (e.g., HLA-DR, LFA-1). We further demonstrate that depletion of Treg results in increased S. Typhi-specific cytokine production by CD8+ TEM in vitro. These results suggest that the tissue distribution of activated Treg, their characteristics and activation status may play a pivotal role in typhoid fever, possibly through suppression of S. Typhi-specific effector T cell responses. These studies provide important novel insights into the regulation of immune responses that are likely to be critical in protection against typhoid and other enteric infectious diseases.

Type 1 narcolepsy is caused by deficiency of hypothalamic orexin/hypocretin. An autoimmune basis is suspected, but no specific antibodies, either causative or as biomarkers, have been identified. However, the AS03 adjuvanted split virion H1N1 (H1N1-AS03) vaccine, created to protect against the 2009 Pandemic, has been implicated as a trigger of narcolepsy particularly in children. Sera and CSFs from 13 H1N1-AS03-vaccinated patients (12 children, 1 young adult) with type 1 narcolepsy were tested for autoantibodies to known neuronal antigens including the N-methyl-D-aspartate receptor (NMDAR) and contactin-associated protein 2 (CASPR2), both associated with encephalopathies that include disordered sleep, to rodent brain tissue including the lateral hypothalamus, and to live hippocampal neurons in culture. When sufficient sample was available, CSF levels of melanin-concentrating hormone (MCH) were measured. Sera from 44 H1N1-ASO3-vaccinated children without narcolepsy were also examined. None of these patients' CSFs or sera was positive for NMDAR or CASPR2 antibodies or binding to neurons; 4/13 sera bound to orexin-neurons in rat brain tissue, but also to other neurons. MCH levels were a marginally raised (n = 8; p = 0.054) in orexin-deficient narcolepsy patients compared with orexin-normal children (n = 6). In the 44 H1N1-AS03-vaccinated healthy children, there was no rise in total IgG levels or in CASPR2 or NMDAR antibodies three weeks following vaccination. In conclusion, there were no narcolepsy-specific autoantibodies identified in type 1 narcolepsy sera or CSFs, and no evidence for a general increase in immune reactivity following H1N1-AS03 vaccination in the healthy children. Antibodies to other neuronal specific membrane targets, with their potential for directing use of immunotherapies, are still an important goal for future research.

Following the introduction of effective protein-polysaccharide conjugate vaccines against capsular group C meningococcal disease in Europe, meningococci of capsular group B remain a major cause of death and can result in debilitating sequelae. The outer membrane proteins PorA and FetA have previously been shown to induce bactericidal antibodies in humans. Despite considerable antigenic variation among PorA and FetA OMPs in meningococci, systematic molecular epidemiological studies revealed this variation is highly structured so that a limited repertoire of antigenic types is congruent with the hyperinvasive meningococcal lineages that have caused most of the meningococcal disease in Europe in recent decades. Here we describe the development of a prototype vaccine against capsular group B meningococcal infection based on a N. meningitidis isolate genetically engineered to have constitutive expression of the outer membrane protein FetA. Deoxycholate outer membrane vesicles (dOMVs) extracted from cells cultivated in modified Frantz medium contained 21.8% PorA protein, 7.7% FetA protein and 0.03 μg LPS per μg protein (3%). The antibody response to the vaccine was tested in three mouse strains and the toxicological profile of the vaccine was tested in New Zealand white rabbits. Administration of the vaccine, MenPF-1, when given by intramuscular injection on 4 occasions over a 9 week period, was well tolerated in rabbits up to 50 μg/dose, with no evidence of systemic toxicity. These data indicated that the MenPF-1 vaccine had a toxicological profile suitable for testing in a phase I clinical trial.

Invasive meningococcal disease causes over 3500 cases each year in Europe, with particularly high incidence among young children. Among serogroup B meningococci, which cause most of the cases, high diversity in the outer membrane proteins (OMPs) is observed in endemic situations; however, comprehensive molecular epidemiological data are available for the diversity and distribution of the OMPs PorA and FetA and these can be used to rationally design a vaccine with high coverage of the case isolates. The aim of this study was to determine whether outer membrane vesicles (OMVs) derived from an isolate with constitutive FetA expression (MenPF-1 vaccine) could be used to induce antibodies against both the PorA and FetA antigens. The immunogenicity of various dose levels and number of doses was evaluated in mice and rabbits, and IgG antibody responses tested against OMVs and recombinant PorA and FetA proteins. A panel of four isogenic mutants was generated and used to evaluate the relative ability of the vaccine to induce serum bactericidal activity (SBA) against FetA and PorA. Sera from mice were tested in SBA against the four target strains. Results demonstrated that the MenPF-1 OMVs were immunogenic against PorA and FetA in both animal models. Furthermore, the murine antibodies induced were bactericidal against isogenic mutant strains, suggesting that antibodies to both PorA and FetA were functional. The data presented indicate that the MenPF-1 vaccine is a suitable formulation for presenting PorA and FetA OMPs in order to induce bactericidal antibodies, and that proceeding to a Phase I clinical trial with this vaccine candidate is justified.

Invasive pneumococcal disease is one of the major causes of death in young children in resource poor countries. Nasopharyngeal carriage studies provide insight into the local prevalence of circulating pneumococcal serotypes. There are very few data on the concurrent carriage of multiple pneumococcal serotypes. This study aimed to identify the prevalence and serotype distribution of pneumococci carried in the nasopharynx of young healthy Nepalese children prior to the introduction of a pneumococcal conjugate vaccine using a microarray-based molecular serotyping method capable of detecting multi-serotype carriage. We conducted a cross-sectional study of healthy children aged 6 weeks to 24 months from the Kathmandu Valley, Nepal between May and October 2012. Nasopharyngeal swabs were frozen and subsequently plated on selective culture media. DNA extracts of plate sweeps of pneumococcal colonies from these cultures were analysed using a molecular serotyping microarray capable of detecting relative abundance of multiple pneumococcal serotypes. 600 children were enrolled into the study: 199 aged 6 weeks to

Neisseria meningitidis lipopolysaccharide (LPS) has adjuvant properties that can be exploited to assist vaccine immunogenicity. The modified penta-acylated LPS retains the adjuvant properties of hexa-acylated LPS but has a reduced toxicity profile. In this study we investigated whether two modified glycoform structures (LgtE and IcsB) of detoxified penta-acylated LPS exhibited differential adjuvant properties when formulated as native outer membrane vesicles (nOMVs) as compared to the previously described LgtB variant. Detoxified penta-acylated LPS was obtained by disruption of the lpxL1 gene (LpxL1 LPS), and three different glycoforms were obtained by disruption of the lgtB, lgtE or icsB genes respectively. Mice (mus musculus) were immunized with a recombinant PorA P1.7-2,4 (rPorA) protein co-administered with different nOMVs (containing a different PorA serosubtype P1.7,16), each of which expressed one of the three penta-acylated LPS glycoforms. All nOMVs induced IgG responses against the rPorA, but the nOMVs containing the penta-acylated LgtB-LpxL1 LPS glycoform induced significantly greater bactericidal activity compared to the other nOMVs or when the adjuvant was Alhydrogel. Compared to LgtE or IcsB LPS glycoforms, these data support the use of nOMVs containing detoxified, modified LgtB-LpxL1 LPS as a potential adjuvant for future meningococcal protein vaccines.

We measured meningococcal serogroup C (MenC)-specific memory B-cell responses in infants by Enzyme-Linked Immunospot (ELISpot) following different MenC conjugate vaccine schedules to investigate the impact of priming on immune memory.Infants aged 2 months were randomised to receive 1 or 2 doses of MenC-CRM197 at 3 or 3 and 4 months, 1 dose of MenC-TT at 3 months, or no primary MenC doses. All children received a Haemophilus influenzae type b (Hib)-MenC booster at 12 months. Blood was drawn at 5, 12, 12 months +6 days and 13 months of age.Results were available for 110, 103, 76 and 44 children from each group respectively. Following primary immunisations, and prior to the 12-month booster, there were no significant differences between 1- or 2-dose primed children in the number of MenC memory B-cells detected. One month following the booster, children primed with 1 dose MenC-TT had more memory B-cells than children primed with either 1-dose (p = 0.001) or 2-dose (p

In a previous UK multi-center randomized study 278 children received three doses of 7-valent (PCV-7) or 13-valent (PCV-13) pneumococcal conjugate vaccine at 2, 4 and 12 months of age. At 13 months of age, most of these children had pneumococcal serotype-specific IgG concentrations ≥ 0.35 µg/ml and opsonophagocytic assay (OPA) titers ≥ 8.Children who had participated in the original study were enrolled again at 3.5 years of age. Persistence of immunity following infant immunization with either PCV-7 or PCV-13 and the immune response to a PCV-13 booster at pre-school age were investigated.In total, 108 children were followed-up to the age of 3.5 years and received a PCV-13 booster at this age. At least 76% of children who received PCV-7 or PCV-13 in infancy retained serotype-specific IgG concentrations ≥ 0.35 µg/ml against each of 5/7 shared serotypes. For serotypes 4 and 18C, persistence was lower at 22-42%. At least 71% of PCV-13 group participants had IgG concentrations ≥ 0.35 µg/ml against each of 4/6 of the additional PCV-13 serotypes; for serotypes 1 and 3 this proportion was 45% and 52%. In the PCV-7 group these percentages were significantly lower for serotypes 1, 5 and 7F. A pre-school PCV-13 booster was highly immunogenic and resulted in low rates of local and systemic adverse effects.Despite some decline in antibody from 13 months of age, these data suggest that a majority of pre-school children maintain protective serotype-specific antibody concentrations following conjugate vaccination at 2, 4 and 12 months of age.ClinicalTrials.gov NCT01095471.