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Background. After immunization with serogroup C meningococcal (MenC) conjugate vaccine, antibody responses and vaccine effectiveness are sustained in adolescents, in contrast to rapid waning in young children. We investigated the persistence of serum bactericidal antibody (SBA) titers in children 6 years after immunization with MenC vaccine (primed between 2 months and 6 years of age). The response to a Haemophilus influenzae type b-MenC conjugate (Hib-MenC) booster was also measured. Methods. A phase 4 clinical trial was conducted among 250 healthy 6-12-year-old children. SBA titers were measured before, 1 month after, and 1 year after Hib-MenC administration. The correlate of protection was an SBA titer of ⩾8. Results. An SBA titer of ⩾8 was observed in 61 (25% [95% confidence interval (CI), 20%-30%]) of 244 participants (mean age, 9.1 years; mean interval since MenC immunization, 6.75 years). The proportion with an SBA titer of ⩾8 and the SBA geometric mean titer increased with age, from 12% (95% CI, 4%-23%) to 48% (95% CI, 29%-67%) and from 2.90 (95% CI, 2.11-3.99) to 17.20 (95% CI, 6.80-43.5), respectively, from a mean age of 7.0 to 12.1 years. One month after the Hib-MenC booster, all participants had an SBA titer of ⩾8, which was sustained in 99.6% at 1 year. Conclusions. As a result of waning antibody, the majority of 6-12-year-old children in the United Kingdom have inadequate serological protection against MenC. The persistence of MenC immunity and the response to a Hib-MenC booster is dependent on age at priming. A booster was highly effective in this cohort and could sustain population immunity against MenC disease. [ABSTRACT FROM AUTHOR]

Background. A resurgence of Haemophilus influenzae type b (Hib) disease occurred in the United Kingdom between 1999 and 2003 and was partially attributed to lower immunogenicity of combination vaccines. The reservoir for Hib that led to transmission in this period is unknown. Methods. We estimated the point prevalence of Hib carriage in school-aged children and adults, using oropharyngeal swabbing and selective media. We characterized the Hib isolates by multilocus sequence typing (MLST) and measured Hib antibody concentrations in adults by enzyme-linked immunosorbent assay. Results. Point prevalence for Hib carriage in 855 children aged 6-16 years was 4.2% (95% confidence interval [CI], 2.5%-5.9%). Five clonal groups of Hib were identified by MLST, 86% from the lineage of sequence type 6. No Hib was isolated in 385 adults (upper limit of 95% CI, 0.95%). The geometric mean concentration of serum antibody to polyribosylribitol phosphate was 0.47 μg/mL (95% CI, 0.37- 0.59 μg/mL) in adults. Conclusions. Hib carriage is common in school-aged children, who are a significant reservoir for ongoing transmission of Hib to susceptible individuals in the United Kingdom. Surveillance of transmission and immunity across all ages of the population is essential to monitor the evolution of Hib epidemiology. [ABSTRACT FROM AUTHOR]

Objectives: The aims of this study were to assess aetiology and clinical characteristics in childhood meningitis, and develop clinical decision rules to distinguish bacterial meningitis from other similar clinical syndromes., Methods: Children aged <16 years hospitalised with suspected meningitis/encephalitis were included, and prospectively recruited at 31 UK hospitals. Meningitis was defined as identification of bacteria/viruses from cerebrospinal fluid (CSF) and/or a raised CSF white blood cell count. New clinical decision rules were developed to distinguish bacterial from viral meningitis and those of alternative aetiology., Results: The cohort included 3002 children (median age 2·4 months); 1101/3002 (36·7%) had meningitis, including 180 bacterial, 423 viral and 280 with no pathogen identified. Enterovirus was the most common pathogen in those aged <6 months and 10-16 years, with Neisseria meningitidis and/or Streptococcus pneumoniae commonest at age 6 months to 9 years. The Bacterial Meningitis Score had a negative predictive value of 95·3%. We developed two clinical decision rules, that could be used either before (sensitivity 82%, specificity 71%) or after lumbar puncture (sensitivity 84%, specificity 93%), to determine risk of bacterial meningitis., Conclusions: Bacterial meningitis comprised 6% of children with suspected meningitis/encephalitis. Our clinical decision rules provide potential novel approaches to assist with identifying children with bacterial meningitis., Funding: This study was funded by the Meningitis Research Foundation, Pfizer and the NIHR Programme Grants for Applied Research., Competing Interests: Declaration of Competing Interest MS has been an investigator on projects funded by GlaxoSmithKline, Merck, Moderna, Pfizer, Sanofi-Pasteur, Seqirus, Symvivo and VBI Vaccines. All funds have been paid to his institute, and he has not received any personal payments. AJP was a member of the World Health Organisation’s Strategic Advisory Group of Experts on Immunisation until January 2022 and remains chair of the UK Department of Health and Social Care's Joint Committee on Vaccination and Immunisation (JCVI). AJP also reports providing advice to Shionogi on COVID-19, and funding from the National Institute for Health Research (NIHR), AstraZeneca, the Bill & Melinda Gates Foundation, Wellcome, the Medical Research Council, and the Coalition for Epidemic Preparedness Innovations (CEPI). Oxford University has entered into a partnership with AstraZeneca for the development of COVID-19 vaccines. TS is Director of The Pandemic Institute, which has received funding from Innova, CSL Seqirus, Aviva and DAM Health; was an advisor to the GSK Ebola Vaccine programme and the Siemens Diagnostic Programme; Co-Chaired the WHO Neuro-COVID task force and sat on the UK Government’s Advisory Committee on Dangerous Pathogens, and the Medicines and Healthcare Products Regulatory Agency (MHRA) Expert Working Group on Covid-19 vaccines. PH has been an investigator on projects funded by GlaxoSmithKline, Merck, Moderna, Pfizer, Sanofi-Pasteur, Novavax, Valneva, Minervax and AZ. All funds have been paid to his institute, and he has not received any personal payments. He is a member of the UK JCVI. All other authors have no COI to disclose., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

It is now widely accepted that multiple imputation (MI) methods properly handle the uncertainty of missing data over single imputation methods. Several standard statistical software packages, such as SAS, R and STATA, have standard procedures or user-written programs to perform MI. The performance of these packages is generally acceptable for most types of data. However, it is unclear whether these applications are appropriate for imputing data with a large proportion of zero values resulting in a semi-continuous distribution. In addition, it is not clear whether the use of these applications is suitable when the distribution of the data needs to be preserved for subsequent analysis. This article reports the findings of a simulation study carried out to evaluate the performance of the MI procedures for handling semi-continuous data within these statistical packages. Complete resource use data on 1060 participants from a large randomized clinical trial were used as the simulation population from which 500 bootstrap samples were obtained and missing data imposed. The findings of this study showed differences in the performance of the MI programs when imputing semi-continuous data. Caution should be exercised when deciding which program should perform MI on this type of data.