Search

Meningoencephalitis following yellow fever vaccination is considered a viral neuroinvasive disease. We describe three patients with typical autoimmune encephalitis syndromes that developed 1-27 days following yellow fever vaccination. Anti-N-methyl-d-aspartate-r antibodies were identified in the CSF and serum of two patients and the other case was associated with anti-neurexin-3 antibodies. One case was confirmed as vaccine-associated neurotropic disease due to reactive CSF yellow fever IgM, which suggested an infectious-autoimmune overlap mechanism. Two aditional cases of Anti-N-methyl-d-aspartate-r encephalitis were identified in the literature review. Antibody-positive autoimmune encephalitis should be included in the differential diagnosis of neurologic adverse events following yellow fever vaccination., (Copyright © 2021 Elsevier B.V. All rights reserved.)

The yellow fever vaccine (YF17DD) is highly effective with a single injection conferring protection for at least 10 years. The YF17DD induces polyvalent responses, with a TH1/TH2 CD4 + profile, robust T CD8 + responses, and synthesis of interferon-gamma (IFN-γ), culminating in high titers of neutralizing antibodies. Furthermore, C-type lectin domain containing 5A (CLEC5A) has been implicated in innate outcomes in other flaviviral infections. Here, we conducted a follow-up study in volunteers immunized with YF17DD, investigating the humoral response, cellular phenotypes, gene expression, and single nucleotide polymorphisms (SNPs) of IFNG and CLEC5A, to clarify the role of these factors in early response after vaccination. Activation of CLEC5A + monocytes occurred five days after vaccination (DAV). Following, seven DAV data showed activation of CD4 + and CD8 + T cells together with early positive correlations between type II IFN and genes of innate antiviral response (STAT1, STAT2, IRF7, IRF9, OAS1, and RNASEL) as well as antibody levels. Furthermore, individuals with genotypes rs2430561 AT/AA, rs2069718 AG/AA (IFNG), and rs13237944 AC/AA (CLEC5A), exhibited higher expression of IFNG and CLEC5A, respectively. Together, we demonstrated that early IFN-γ and CLEC5A responses, associated with rs2430561, rs2069718, and rs13237944 genotypes, may be key mechanisms in the long-lasting immunity elicited by YF17DD.

Purpose : To report the manifestation of Vogt-Koyanagi-Harada- like disease (VKH) following yellow fever vaccination. Methods : Case report. Results : A 34-year-old immunocompetent male had tinnitus, headache, and decreased vision after a booster dose of yellow fever vaccine. Visual acuity was 20/100 in the right eye and 20/80 in the left, with serous retinal detachment (SRD) and choroidal thickening identified on clinical examination and multimodal imaging. Lumbar puncture revealed pleocytosis and an increased protein content, but extensive investigations ruled out infectious/neurological diseases. Pulse intravenous methylprednisolone was given, followed by a tapering regimen of high-dose oral prednisone. Azathioprine was started early, 3 weeks after initiation of oral steroids. Intraocular inflammation and SRD rapidly resolved, with visual acuity reaching 20/20 in both eyes, after 3 weeks. No recurrence of intraocular inflammation or sign of depigmentation was so far noticed, at 2 years of follow-up. Conclusion : Yellow fever vaccine may be a possible trigger for VKH.

Members of the flavivirus genus share a high level of sequence similarity and often circulate in the same geographical regions. However, whether T cells induced by one viral species cross-react with other related flaviviruses has not been globally addressed. In this study, we tested pools of epitopes derived from dengue (DENV), Zika (ZIKV), Japanese encephalitis (JEV), West Nile (WNV), and yellow fever (YFV) viruses by intracellular cytokine staining (ICS) using peripheral blood mononuclear cells (PBMCs) of individuals naturally exposed to DENV or immunized with DENV (TV005) or YF17D vaccine. CD8 T cell responses recognized epitopes from multiple flaviviruses; however, the magnitude of cross-reactive responses was consistently severalfold lower than those to the autologous epitope pools and was associated with lower expression of activation markers such as CD40L, CD69, and CD137. Next, we characterized the antigen sensitivity of short-term T cell lines (TCL) representing 29 different individual epitope/donor combinations. TCL derived from DENV monovalent vaccinees induced CD8 and CD4 T cells that cross-reacted within the DENV serocomplex but were consistently associated with >100-fold-lower antigen sensitivity for most other flaviviruses, with no cross-recognition of YFV-derived peptides. CD8 and CD4 TCL from YF17D vaccinees were associated with very limited cross-reactivity with any other flaviviruses and in five out of eight cases >1,000-fold-lower antigen sensitivity. Overall, our data suggest limited cross-reactivity for both CD4 and CD8 T cell responses between flaviviruses and have implications for understanding immunity elicited by natural infection and strategies to develop live attenuated vaccines against flaviviral species. IMPORTANCE The envelope (E) protein is the dominant target of neutralizing antibodies for dengue virus (DENV) and yellow fever virus (YFV). Accordingly, several DENV vaccine constructs use the E protein in a live attenuated vaccine format, utilizing a backbone derived from a heterologous flavivirus (such as YF) as a delivery vector. This backbone comprises the nonstructural (NS) and capsid (C) antigens, which are dominant targets of T cell responses. Here, we demonstrate that cross-reactivity at the level of T cell responses among different flaviviruses is very limited, despite high levels of sequence homology. Thus, the use of heterologous flavivirus species as a live attenuated vaccine vector is not likely to generate optimal T cell responses and might thus impair vaccine performance., (Copyright © 2020 American Society for Microbiology.)

Background: Childhood vaccination in Ghana has historically been high, but the impact of recently introduced vaccines on coverage is unknown. We calculate vaccine coverage of Ghanaian children- contrasting newly introduced vaccines and those long available - and describe associations between sociodemographic indicators and full vaccination., Methods: Data from the 2014 Ghana Demographic and Health Survey was used to calculate full vaccination, defined as receipt of one dose bacillus Calmette-Guérin (BCG); two doses of rotavirus vaccine; 3 doses of pentavalent vaccine, oral polio vaccine (OPV), and pneumococcal conjugate vaccine (PCV); and one dose of measles-rubella vaccine and yellow fever vaccine, among children age 12-24 months. Logistic regression with survey procedures was used to estimate odds ratios for socioeconomic factors' association with full vaccination., Results: The sample comprised a total of 1107 children 12-24 months. Full vaccination coverage was 70.8%. Vaccination coverage was higher for vaccines administered at younger ages (e.g., birth dose of BCG was 97.0%) than at older ages (e.g., yellow fever at 9 months was 88.2%). Newly introduced vaccines had lower coverage: at 10 weeks, pentavalent 2 was 95.4%, versus 91.2% for PCV 2 and 88.8% for rotavirus 2. Living outside of Greater Accra, home delivery, younger maternal age, urban residence, and more than one child under five in the home were all associated with decreased odds of full vaccination in the adjusted analysis whereas sex of the child, wealth, religion, and maternal education were not associated with full vaccination status., Conclusion: Ghana has high overall vaccination rates although disparities in full vaccination by sociodemographic status exist. As vaccine recommendations are revised, it will be important to insure equitable access to vaccination for all children regardless of demographic and socioeconomic background., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Background: Yellow fever vaccine exists for over 80 years and is considered to be relatively safe. However, in rare cases it can produce serious neurotropic and viscerotropic complications. We report a case of a patient who presented both viscerotropic and neurological manifestations after yellow fever vaccination., Case Presentation: We describe the case of a 37 years old man who developed after the yellow fever vaccination a yellow fever vaccine-associated viscerotropic disease followed by acute uveitis. Prolonged detection of yellow fever RNA in blood and urine was consistent with yellow fever vaccine-associated adverse event. The final outcome was good, although with persistent fatigue over a few months., Conclusions: Even if the yellow fever vaccine is relatively safe, physicians should be aware of its possible serious adverse effects.

Introduction: The strategy to Eliminate Yellow Fever Epidemics (EYE) is a global initiative that includes all countries with risk of yellow fever (YF) virus transmission. Of these, 40 countries (27 in Africa and 13 in the Americas) are considered high-risk and targeted for interventions to increase coverage of YF vaccine. Even though the World Health Organization (WHO) recommends that YF vaccine be given concurrently with the first dose of measles-containing vaccine (MCV1) in YF-endemic settings, estimated coverage for MCV1 and YF vaccine have varied widely. The objective of this study was to review global data sources to assess discrepancies in YF vaccine and MCV1 coverage and identify plausible reasons for these discrepancies., Methods: We conducted a desk review of data from 34 countries (22 in Africa, 12 in Latin America), from 2006 to 2016, with national introduction of YF vaccine and listed as high-risk by the EYE strategy. Data reviewed included procured and administered doses, immunization schedules, routine coverage estimates and reported vaccine stock-outs. In the 30 countries included in the comparitive analysis, differences greater than 3 percentage points between YF vaccine and MCV1 coverage were considered meaningful., Results: In America, there were meaningful differences (7-45%) in coverage of the two vaccines in 6 (67%) of the 9 countries. In Africa, there were meaningful differences (4-27%) in coverage of the two vaccines in 9 (43%) of the 21 countries. Nine countries (26%) reported MVC1 stock-outs while sixteen countries (47%) reported YF vaccine stock-outs for three or more years during 2006-2016., Conclusion: In countries reporting significant differences in coverage of the two vaccines, differences may be driven by different target populations and vaccine availability. However,these were not sufficient to completely explain observed differences. Further follow-up is needed to identify possible reasons for differences in coverage rates in several countries where these could not fully be explained., (Published by Elsevier Ltd.)

Introduction: Yellow fever is a vector-borne disease in sub-Saharan Africa and tropical South America regions which is preventable by an effective and safe vaccine. In some cases, it may cause serious adverse effects and should therefore be prescribed only to individuals at risk of exposure to the yellow fever virus or those traveling to countries requiring proof of vaccination. The aim of this study was to analyze the prescriptions of yellow fever vaccine, based on travel destination and type of referring consultation, according to the international recommendations of the World Health Organization., Material and Methods: The database of the International Vaccination Centre of the International Vaccination Centre of the Loures-Odivelas Health Centre Group was used to analyze data concerning the year of 2016. Travelers who were prescribed and administered the yellow fever vaccine were grouped based on travel destination and type of referring consultation (travelers' medical consultations or non-specialist consultations)., Results: A total of 517 yellow fever vaccines were administered, with the highest proportion in female (53%) and in individuals aged 40 - 49 years (20.7%). One hundred and thirteen (22.6%) of the 499 individuals with known-destinations were travelling to non-endemic/non-epidemic countries and a greater proportion of those were prescribed in non-specialist consultations (27.3%) than in travel medicine consultations (8.8%)., Discussion/conclusion: The highest percentage of yellow fever vaccines that were administered to individuals travelling to non-endemic/non-epidemic countries were prescribed in non-specialist consultations.

Background: Since 2016 outbreaks of yellow fever are reported in Brazil. This is a risk to unvaccinated travellers in that area., Case Description: In early January, an unvaccinated traveller returning from São Paulo attended our outpatient clinic complaining of symptoms later diagnosed as yellow fever. The disease manifested itself as fever, lower back pain, nausea and highly elevated liver enzymes. A yellow fever infection has multiple stages. The first stage is acute infection which merges into the second stage which is when improvement occurs. Either improvement continues or transfers into a third stage which is characterized by multi-organ failure. In this particular patient, stage three did not occur., Conclusion: The goal of this case report is to show that vaccination against yellow fever is the most important preventive measure when travelling to an area where the yellow fever virus is in circulation. Yellow fever should not be forgotten in the differential diagnosis of a traveller with fever.

Background: More than 700,000 trips were made by residents in England, Wales, and Northern Ireland (EWNI) in 2015 to tropical countries endemic for yellow fever, a potentially deadly, yet vaccine-preventable disease transmitted by mosquitoes. The aim of this study was to map the geographical accessibility of yellow fever vaccination centres (YFVC) in EWNI., Methods: The location of 3208 YFVC were geocoded and the average geodetic distance to nearest YFVC was calculated for each population unit. Data on trips abroad and centres were obtained regionally for EWNI and nationally for the World Top20 countries in terms of travel., Results: The mean distance to nearest YFVC was 2.4 km and only 1% of the population had to travel more than 16.1 km to their nearest centre. The number of vaccines administered regionally in EWNI was found correlated with the number of trips to yellow fever countries. The number of centres per 100,000 trips was 6.1 in EWNI, which was below United States (12.1) and above the rest of Top20 countries., Conclusions: The service availability was in line with demand regionally. With the exception of remote, rural areas, yellow fever vaccination services were widely available with only short distances to cover for the travelling public., (Crown Copyright © 2017. Published by Elsevier Ltd. All rights reserved.)

Objective: Analyze the impact of educational level, negative beliefs and negative attitudes on the yellow fever vaccination coverage (YFVC)., Methodology: This analytical study involved a sample of 2763 people from 866 households. Educational status was described in six levels: No level (Respondent had never attended school), level-1 (respondent left before intermediate school), level-2 (Respondent attended intermediate school), level-3 (respondent attended high school), level-4 (Respondent attended university), Other level (When the level could not be determined). The Attitude towards vaccination was described in terms of person's availability to recommend vaccination to third. The relationships were analyzed by multivariate mixed logistic regression., Results: Among the 2763 peoples, 2039 (73.8%) were vaccinated against yellow fever. People who left high school with or without the French baccalaureate were more likely to be vaccinated against YF than people without any diploma (OR = 1.4; p < 0.05). The probability of being vaccinated among people with negative attitudes was reduced by 40% (OR = 0.6; p < 0.05)., Conclusion: Low level of education, negative beliefs and negative attitudes have significant impacts on YFVC. Negatives beliefs and attitudes result often from a major lack of information about the benefits of vaccination. This deficit is exacerbated in persons with low educational level., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Purpose: To assess those published cases of yellow fever (YF) vaccine-associated viscerotropic disease that meet the Brighton Collaboration criteria and to assess the safety of YF vaccine with respect to viscerotropic disease., Literature Search: Ten electronic databases were searched with no restriction of date or language and reference lists of retrieved articles., Methods: All abstracts and titles were independently read by two reviewers and data independently entered by two reviewers., Results: All serious adverse events that met the Brighton Classification criteria were associated with first YF vaccinations. Sixty-two published cases (35 died) met the Brighton Collaboration viscerotropic criteria, with 32 from the US, six from Brazil, five from Peru, three from Spain, two from the People's Republic of China, one each from Argentina, Australia, Belgium, Ecuador, France, Germany, Ireland, New Zealand, Portugal, and the UK, and four with no country stated. Two cases met both the viscerotropic and YF vaccine-associated neurologic disease criteria. Seventy cases proposed by authors as viscerotropic disease did not meet any Brighton Collaboration viscerotropic level of diagnostic certainty or any YF vaccine-associated viscerotropic disease causality criteria (37 died)., Conclusion: Viscerotropic disease is rare in the published literature and in pharmacovigilance databases. All published cases were from developing countries. Because the symptoms are usually very severe and life threatening, it is unlikely that cases would not come to medical attention (but might not be published). Because viscerotropic disease has a highly predictable pathologic course, it is likely that viscerotropic disease post-YF vaccine occurs in low-income countries with the same incidence as in developing countries. YF vaccine is a very safe vaccine that likely confers lifelong immunity., Competing Interests: The author reports no conflicts of interest in this work.

Background: The adverse effects of yellow fever (YF) vaccine in dialysis patients are not well known. There is concern about the risks and benefits of the vaccine in immunocompromised patients living in endemic areas, particularly given the risk of resurgence of urban YF with the spread of Aedes aegypti mosquitoes. The purpose of this study was to assess the coverage and safety of YF vaccine in chronic dialysis patients., Methods: A cross-sectional study of 130 chronic dialysis patients was performed. Data were collected on clinical characteristics and YF vaccine status. Patients not vaccinated against YF or without a booster vaccination within the last 10 years were referred to receive the vaccine, and adverse effects were monitored., Results: Previous vaccination was verified in 44 patients within the last 10 years and in 26 patients at more than 10 years ago, with no mention of adverse effects. Thirty-six patients had never been vaccinated and 24 had an unknown vaccination status. Of the total 86 patients referred for immunization, 45 actually received the YF vaccine, with 24.4% experiencing mild local adverse effects and 4.4% experiencing fever. No serious adverse effects attributable to YF vaccine were observed (anaphylaxis, neurological or viscerotropic disease)., Conclusions: YF vaccine coverage among hemodialysis patients is low, and the vaccine appeared to be safe in this population with a small sample size., (Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Background: Yellow fever (YF) is a mosquito-borne disease, which can be prevented by vaccination. While YF vaccination (YFV) is not generally recommended for travellers to Tanzania, proof of YFV may be required upon arrival. In April 2013, the World Health Organization concluded that one dose of YFV confers lifelong protection and countries have started to adapt their entry requirements. The traveller's consultant has to balance the risk of YFV and the risk of encountering problems when entering a country without a valid YFV, especially because countries are slowly implementing the requirements., Methods: We performed a survey among 421 travellers to Tanzania with a pre-travel consultation at the Travel Clinic of the University of Zurich about their experiences with YFV certificate inspections upon arrival in Tanzania between January and November 2015., Results: There were three main findings: (i) most vaccine card checks were done while crossing the land border of Tanzania. Inspections were frequently conducted at Arusha airport, less often in Dar es Salaam and Zanzibar. In the latter a significantly larger percentage of individuals arriving by ferry/boat were checked than those arriving by plane. (ii) Checks appeared to be non-systematic. They were also performed in travellers who did not enter Tanzania from a YF-endemic country. No seasonal or daytime pattern could be identified; the thoroughness of checks varied widely. (iii) In the case of travel without valid YFV, an exemption certificate was always accepted. In travellers with neither a valid YFV nor an exemption certificate, travellers reported forced YF vaccination and fines before entry was granted., Conclusions: We recommend YFV or a YF exemption certificate for all travellers to Tanzania until further notice. The decision of whether to vaccinate against YF or to issue an exemption should be based on exposure risk to YF infection in other countries during travel., (© International Society of Travel Medicine, 2016. All rights reserved. Published by Oxford University Press. For permissions, please e-mail: journals.permissions@oup.com.)

Background: People who travel while immunocompromised are more at risk of serious travel-related infection. Their condition, medications or treatments can contraindicate, decrease the effectiveness of or increase the toxicity of vaccinations or malaria chemoprophylaxis. Therefore, immunocompromised travellers require careful assessment and specialized pre-travel advice. The aims of this study were to investigate enquiries by healthcare professionals (HCPs) to the UK National Travel Health Network and Centre (NaTHNaC) advice line regarding travellers with immunocompromise and to identify their most common concerns., Methods: Documentation for all calls taken by advisers at the London office during 2013 was reviewed., Results: Of the 4910 enquiries to the London NaTHNaC advice line, 397 calls concerned immunocompromised travellers (8.1%). The majority of immunocompromised travellers were planning to visit Sub-Saharan Africa (53%) for the purpose of tourism (43%). Sixty-seven percent of enquiries concerned vaccine use, 11% were about malaria chemoprophylaxis, 20% were about both and 2% were for other reasons. Causes of immunocompromise included inflammatory or autoimmune conditions (43%), cancer (18%), splenic dysfunction (13%), immunosuppressive drugs (12%), human immunodeficiency virus (11%), primary immunodeficiency (1%), neutropenia (0.5%) and thymus abnormalities (0.5%)., Conclusions: There were frequent enquires to the advice line by UK HCPs regarding immunocompromised travellers. The travellers in this study had a wide range of underlying medical conditions and varying levels of immunocompromise. These enquiries may reflect a lack of clarity in current national guidelines, difficulties in interpreting them or both. Establishing the reasons for these deficiencies as well as the reasons behind UK HCP concerns and lack of confidence requires further investigation. This research has highlighted potential knowledge gaps and will help inform future guidance and educational activities for UK HCPs advising travellers., (© International Society of Travel Medicine, 2016. All rights reserved. Published by Oxford University Press. For permissions, please e-mail: journals.permissions@oup.com.)

Background: The Department of Health regulates the designation of yellow fever vaccination centres (YFVCs) in the Republic of Ireland to ensure appropriate standards in the safe, effective use of yellow fever vaccine for overseas travellers. The process of designation of YFVCs is delegated to Directors of Public Health who direct Principal Medical Officers. Variation in implementation of specific criteria for designation exists and no formal follow up inspection is carried out. This survey of all designated YFVCs in the Republic of Ireland aimed to assess compliance with standards to ensure the objectives of the national yellow fever vaccination programme were met., Methods: A piloted questionnaire devised from a United Kingdom (UK) YFVC survey was developed and tested in five YFVCs. The questionnaire was adapted for the postal survey and captured data on professional training, reference sources, services provided, physical facilities and supplies, and was distributed to 655 YFVCs in a stamped addressed envelope., Results: During the period 2010-2011, there were 655 designated YFVCs in the Republic of Ireland. Responses were received from 246 centres (38% response rate), 91% of which were in general practice. Deficiencies were identified in respect of vaccine refrigeration protocols, record keeping, attendance at YFVC training sessions, and clinical protocols for adverse events., Conclusions: Specific deficiencies in relation to training, vaccine storage, administration and documentation should be addressed to ensure standardised YFVC practices and thus align them with best international practice., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

As a consequence of YF outbreaks that hit Brazil, Argentina, and Paraguay in 2008-2009, a significant demand for YF vaccination was subsequently observed in Argentina, a country where the usual vaccine recommendations are restricted to provinces that border Brazil, Paraguay, and Bolivia. The goal of this paper is to describe the adverse events following immunization (AEFI) against YF in Argentina during the outbreak in the northeastern province of Misiones, which occurred from January 2008 to January 2009. During this time, a total of nine cases were reported, almost two million doses of vaccine were administered, and a total of 165 AEFI were reported from different provinces. Case study analyses were performed using two AEFI classifications. Forty-nine events were classified as related to the YF vaccine (24 serious and 1 fatal case), and 12 events were classified as inconclusive. As the use of the YF 17D vaccine can be a challenge to health systems of countries with different endemicity patterns, a careful clinical and epidemiological evaluation should be performed before its prescription to minimize serious adverse events., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Yellow fever vaccine-associated viscerotropic disease (YEL-AVD) is a rare and serious adverse event of the yellow fever (YF) vaccine that mimics wild-type YF. Research shows there may be an increased risk of YEL-AVD among the elderly population (≥ 60-65 years old), however this research has yet to be accumulated and reviewed in order to make policy recommendations to countries currently administering the YF vaccine. This paper systematically reviewed all information available on YEL-AVD to determine if there is an increased risk among the elderly, for both travelers and endemic populations. Age-specific reporting rates (RRs) were re-calculated from the literature using the Brighton Collaboration case definition for YEL-AVD and were then analyzed to determine if there was a significant difference between the RRs of younger and older age groups. Two out of the five studies found a significantly higher rate of YEL-AVD among the elderly population. Our findings suggest unexposed elders may be at an increased risk of developing YEF-AVD, however the evidence remains limited. Therefore, our findings for YF vaccination of elderly populations support the recommendations made by the Strategic Advisory Group of Experts (SAGE) in their April 2013 meeting, mainly vaccination of the elderly should be based on a careful risk-benefit analysis., (Copyright © 2013 World Health Organization (WHO). Published by Elsevier Ltd.. All rights reserved.)

Purpose: Approximately 50,000 adults die annually from vaccine-preventable diseases in the United States. Most traditional vaccine providers (eg, physician offices) administer vaccinations during standard clinic hours, but community pharmacies offer expanded hours that allow patients to be vaccinated at convenient times. We analyzed the types of vaccines administered and patient populations vaccinated during off-clinic hours in a national community pharmacy, and their implications for vaccination access and convenience., Methods: We retrospectively reviewed data for all vaccinations given at the Walgreens pharmacy chain between August 2011 and July 2012. The time of vaccination was categorized as occurring during traditional hours (9:00 am-6:00 pm weekdays) or off-clinic hours, consisting of weekday evenings, weekends, and federal holidays. We compared demographic characteristics and types of vaccine. We used a logistic regression model to identify predictors of being vaccinated during off-clinic hours., Results: During the study period, pharmacists administered 6,250,402 vaccinations, of which 30.5% were provided during off-clinic hours: 17.4% were provided on weekends, 10.2% on evenings, and 2.9% on holidays. Patients had significantly higher odds of off-clinic vaccination if they were younger than 65 years of age, were male, resided in an urban area, and did not have any chronic conditions., Conclusions: A large proportion of adults being vaccinated receive their vaccines during evening, weekend, and holiday hours at the pharmacy, when traditional vaccine providers are likely unavailable. Younger, working-aged, healthy adults, in particular, a variety of immunizations during off-clinic hours. With the low rates of adult and adolescent vaccination in the United States, community pharmacies are creating new opportunities for vaccination that expand access and convenience.

Objective: To verify if the Bio-Manguinhos 17DD yellow fever vaccine (17DD-YFV) used in lower doses is as immunogenic and safe as the current formulation., Results: Doses from 27,476 IU to 587 IU induced similar seroconversion rates and neutralizing antibodies geometric mean titers (GMTs). Immunity of those who seroconverted to YF was maintained for 10 mo. Reactogenicity was low for all groups., Methods: Young and healthy adult males (n = 900) were recruited and randomized into 6 groups, to receive de-escalating doses of 17DD-YFV, from 27,476 IU to 31 IU. Blood samples were collected before vaccination (for neutralization tests to yellow fever, serology for dengue and clinical chemistry), 3 to 7 d after vaccination (for viremia and clinical chemistry) and 30 d after vaccination (for new yellow fever serology and clinical chemistry). Adverse events diaries were filled out by volunteers during 10 d after vaccination. Volunteers were retested for yellow fever and dengue antibodies 10 mo later. Seropositivity for dengue was found in 87.6% of volunteers before vaccination, but this had no significant influence on conclusions., Conclusion: In young healthy adults Bio-Manguinhos/Fiocruz yellow fever vaccine can be used in much lower doses than usual. INTERNATIONAL REGISTER: ISRCTN 38082350.

Introduction: Older age has been associated to serious adverse events (AE) following yellow fever (YF) vaccination in passive surveillance studies, but few prospective studies involving seniors have been published., Results: A total of 906 persons were evaluated; 78 were not vaccinated and 828 received the vaccine; 700 (84.7%) were interviewed after vaccination: 593 (84.7%) did not report any symptoms or signs following YF vaccine; 107 (15.3%) reported at least one AE temporally associated to YF vaccination: 97 (13.9%) had systemic AE and 17 (2.4%) reported AE at the injection site (7 had both systemic and local AE). Data regarding previous vaccination was available for 655 subjects. Statistically significant higher rates of systemic AE were observed among subjects who received the first YF vaccination (17.5%) in comparison to persons who had been previously vaccinated (9.5%)., Methods: This observational prospective study aimed to describe AE following YF vaccination in persons aged ≥ 60 y. From March 2009 to April 2010, seniors who sought YF vaccination at a reference Immunization Center in São Paulo city, Brazil, were included. Demographic and clinical data, previous YF vaccination, travel destination and the final decision regarding YF vaccination or not were collected from standardized medical records. Active AE assessment was done through telephone or electronic mail interview performed approximately 14 d after immunization., Conclusion: Most persons aged ≥ 60 y may be safely vaccinated against YF. Before vaccination, they must be carefully screened for conditions associated to altered immunocompetence and for risk of exposure to YF.

Joyce Skeet outlines the causes of yellow fever and the course of the disease, emphasising the importance of immunisation to control it. She also discusses issues that need to be considered when yellow fever vaccination is provided in primary care.

Vaccinations are an easy and highly effective way to keep travellers healthy. There are few problems with compliance, as all vaccinations are administered pretravel and many vaccines offer protection rates > 95% after a single dose (e.g. hepatitis A, yellow fever). Vaccination of hepatitis A and diphtheriatetanus are recommended for all developing countries. Polio is still indicated for Asia and Africa. Hepatitis B, if possible in combination with A, is recommended for persons travelling for > 30 days, travellers < 35 years, and for people showing special risk behaviour (e.g. high-risk sports, unprotected sexual intercourse). Depending on destination and kind and duration of travel, further vaccinations have to be considered, e.g.: yellow fever (endemic areas, rule of entry), rabies (trekking, travel in remote areas), typhoid fever (Indian sub-continent), meningococcal meningitis (meningitis belt, pilgrims to Saudi-Arabia), tick-borne encephalitis (endemic areas in Europe and Asia), influenza (persons at special risk of complications), Japanese encephalitis (low standard travel in rural areas of Southeast Asia > 30 days), measles (particularly endemic in Africa). Cholera vaccination is virtually never indicated. Several vaccines can be delivered at the same time.

The extent of dissemination of 17D yellow fever vaccine among the population of Kenya, especially among Africans, is estimated, largely from information in the records of the Kenya Medical Department. The total recorded vaccinations of Africans between 1941 and 1951 amount to about 379,000, representing 7.2% of the African population in 1948; it is, however, possible that the actual number of vaccinations is considerably higher. At Mombasa, 78,000 persons of races other than Africans were given routine inoculation over the same period.After a study of the economy of use of vaccine, the author discusses the protection-test surveys performed before 1951 and during that year in relation to the dissemination of vaccine. It is tentatively concluded that natural infection of man with yellow fever is rare in both Kenya and Tanganyika.

Haemagglutination-inhibition tests, which depend on the appearance of haemagglutination-inhibiting antibodies in the serum in virus infections, are in common use in the study of arthropod-borne diseases. This paper contains the results of an investigation into the appearance and pattern of haemagglutination-inhibiting antibodies in the serum of rhesus monkeys inoculated intracerebrally with the 17D strain of yellow fever virus during the testing of seed lots of yellow fever vaccine. These antibodies appeared on the tenth day after inoculation, and were still demonstrable four years later. In all of the eight monkeys tested complement-fixing and neutralizing antibodies against yellow fever antigens also developed, and in six out of the eight heterologous antigens developed.

An earlier study established that Upper Volta children respond to vaccination with the Enders live attenuated measles strain in the same general fashion as do children in the USA. The present report describes a second pilot project carried out in Ouagadougou, Upper Volta. During this investigation various mixtures of live measles, smallpox and 17D yellow fever vaccines were introduced into susceptible infants by jet injection. Combining the attenuated virus vaccines did not alter or accentuate the characteristic clinical reactions elicited by the individual components, nor was there evidence of significant immunological interference. From this experience it is concluded that combined vaccination with these agents may be safely and effectively employed in larger programmes as the need dictates.

The duration of immunity conferred by yellow fever vaccine is as yet undetermined. In this study the neutralizing and haemagglutination-inhibiting antibodies to yellow fever were investigated in 108 persons living in Pouso Alegre, Brazil, where yellow fever has never been reported. These persons had been vaccinated with 17D yellow fever vaccine between 27 December 1940 and 5 February 1941, but not again; and their antibody pattern was compared with that of 78 controls who had never been vaccinated. In the vaccinated group the majority had neutralizing and haemagglutination-inhibiting antibodies present in the serum, whereas in the unvaccinated group antibodies were all but completely absent. Heterologous antibodies to other viruses of Casal's Group B were also found, and the significance of this finding is discussed.

Studies on yellow fever vaccine (YF) in chronic kidney disease (CKD) patients are scarce. This cross-sectional study aimed to evaluate YF neutralizing antibody seroprevalence and titers in previously vaccinated adults with CKD, on dialysis (D-CKD) or not (ND-CKD), compared to healthy persons. The micro Plaque Reduction Neutralization- Horseradish Peroxidase (μPRN-HP) test was used. Antibody titers were expressed as the reciprocal of the highest dilution that neutralized the challenge virus by 50 % (μPRN50). Seropositivity cut-off was set at ≥ 1:100. We included 153 participants: 46 ND-CKD, 50 D-CKD and 57 healthy adults. Median ages were 58.3, 55 and 52.2 years, respectively. Median time since YF vaccination was 22.3, 18.5 and 48.3 months respectively. There were no statistically significant differences in YF seroprevalence and neutralizing antibodies titers among groups: 100 % of ND-CKD; 96 % of D-CKD and 100 % of healthy participants were seropositive. Geometric mean titers (GMT) were 818.5, 683.0 and 665.5, respectively (p = 0.289). [ABSTRACT FROM AUTHOR]

Objective: Evaluate biomarkers capable of safely guiding Yellow fever vaccine (YFV) vaccination among individuals suspicious of hen's egg allergy, and identify factors associated with a higher risk for adverse events after immunization (AEAI). Methods: Patients underwent skin prick test (SPT) for standardized allergens: whole egg, egg white, egg yolk; YFV (1:10 dilution; Biomanguinhos-Fiocruz), and intradermal test (IDT; YFV 0.02 mL, 1:100 dilution) and positive and negative controls. Serum levels of specific IgE (sIgE) for a whole egg, egg white, egg yolk, egg albumin, ovomucoid, lysozyme, and conalbumin (ImmunoCap®; ThermoFisher®) were obtained. Patients sensitized to YFV were submitted to YFV desensitization, and those negatives received YFV (0.5mL) and remained under surveillance for at least one hour. Results: 103 patients were enrolled, 95% under 12 years old. 71% (81/103) of patients had reactions: 80% immediate, 11% mixed, and 9% delayed. There was an association between positive skin test results with YFV and the severity of the reaction (OR:7.64; 95%CI:1.61-36.32; p = 0,011). Only the presence of sIgE to ovomucoid was associated with clinical symptoms (p = 0,025). Thirty patients underwent the YFV desensitization protocol. Conclusion: There is a relationship between the positivity of the egg's components and the severity of the clinical reaction. Furthermore, the relationship between the positivity of the tests with the YFV and egg's components may show a tendency to look at ovomucoid and conalbumin, but it is not a certainty. Therefore, further studies are needed to confirm these associations, and for now, the authors still recommend using the vaccine for testing when necessary. [ABSTRACT FROM AUTHOR]

Background: In 2013, the World Health Organization (WHO) revised their position on yellow fever vaccination, in which revaccination every 10 years was no longer required, and that a single-dose provided life-long protection. However, research data on the immunogenicity of YF vaccine in people aged 60 years and over are scarce. Indeed, immunosenescence may result in lower virus neutralizing antibody titers after primary vaccination and a more rapid waning immunity. Therefore, we tested the hypothesis that older travelers, vaccinated at 60 years or older are more likely to become seronegative in comparison to young adults 10 years after primary YF vaccination.Methods: This is a 10-year follow-up study of an earlier prospective controlled cohort study. In the original trial, the neutralizing antibody response was measured in older travelers (aged 60-81 years, N = 28) and young adults (aged 18-28 years, N = 30) up to 28 days after a primary yellow fever vaccination. Ten years later, we collected serum samples of 22/28 (78%) elderly (71-85 years) and 14/30 (47%) controls (29-40 years), and determined their neutralizing antibody titers by plaque reduction neutralization test (PRNT80). Seropositivity was defined as plaque formation reduction of 80% at a serum dilution of 10 or more (PRNT80 ≥ 10).Results: All participants (36/36) were still seropositive 10 years after primary vaccination. The geometric mean concentrations were not statistically different between the older and younger participants (6.7 IU/mL vs. 8.6 IU/mL, P = 0.5).Conclusions: All older travelers were seropositive, 10 years after a primary YF vaccination at the age of ≥60 years. These data suggest that in older travelers a single vaccination is sufficient to convey long-lasting immunity for at least 10 years, and is in support the position of the WHO on a single-dose yellow fever vaccination. [ABSTRACT FROM AUTHOR]

• This is the first study on the co-administration of typhoid conjugate vaccine (TCV) in West Africa. • Co-administration of TCV with routine vaccines in a typhoid-endemic country was successful. • TCV was safely co-administered at nine months with yellow fever and measles-rubella vaccines. • Single-dose TCV was immunogenic in 9-month-old children. • There was no safety signal related to TCV vaccination or co-administration. In 2017, the World Health Organisation (WHO) pre-qualified a single-dose typhoid conjugate vaccine (TCV) and identified TCV co-administration studies as a research priority. Accordingly, we tested co-administration of Typbar TCV® (Bharat Biotech International) with measles-rubella (MR) and yellow fever (YF) vaccines. We conducted a randomized, double-blind, and controlled, phase 2 trial in Ouagadougou, Burkina Faso. Healthy children aged 9–11 months were randomized 1:1 to receive TCV (Group 1) or control vaccine (inactivated polio vaccine (IPV), Group 2). Vaccines were administered intramuscularly with routine MR and YF vaccines. Safety was assessed by (1) local and systemic reactions on days 0, 3, and 7; (2) unsolicited adverse events within 28 days; and (3) serious adverse events (SAEs) within six months after immunization. We enrolled, randomized, and vaccinated 100 eligible children (49 Group 1 and 51 Group 2). Safety outcomes occurred with similar frequency in both groups: local/solicited reactions (Group 1: 1/49, Group 2: 3/50), systemic/solicited reactions (Group 1: 4/49, Group 2: 9/50), unsolicited adverse events (Group 1: 26/49, Group 2: 33/51), and SAEs (Group 1: 2/49, Group 2: 3/51). TCV conferred robust immunogenicity without interference with MR or YF vaccines. TCV can be safely co-administered with MR and YF vaccines to children at the 9-month vaccination visit. [ABSTRACT FROM AUTHOR]

BackgroundYellow fever (YF) is an acute viral haemorrhagic disease prevalent in tropical Africa and Latin America. The World Health Organization (WHO) estimates that there are 200,000 cases of YF and 30,000 deaths worldwide annually. Treatment for YF is supportive, but a live attenuated virus vaccine is effective for preventing infection. WHO recommends immunisation for all individuals > 9 months living in countries or areas at risk. However, the United States Advisory Committee on Immunization Practices (ACIP) advises that YF vaccine is contraindicated in individuals with HIV. Given the large populations of HIV-infected individuals living in tropical areas where YF is endemic, YF vaccine may be an important intervention for preventing YF in immunocompromised populations.ObjectivesTo assess the risk and benefits of YF immunisation for people infected with HIV.Search methodsWe used standard Cochrane methods to search electronic databases and conference proceedings with relevant search terms without limits to language.Selection criteriaRandomised controlled trials and cohort studies of individuals with HIV infection who received YF vaccine (17DD or 17D-204).Data collection and analysisTwo authors screened abstracts of references identified by electronic or bibliographic searches according to inclusion and exclusion criteria as detailed in the protocol. We identified 199 references and examined 19 in detail for study eligibility. Data were abstracted independently using a standardised abstraction form.Main resultsThree cohort studies were included in the review. They examined 484 patients with HIV infection who received YF immunisation. Patients with HIV infection developed significantly lower concentrations of neutralising antibodies in the first year post immunisation compared to uninfected patients, though decay patterns were similar for recipients regardless of HIV infection. No study patient with HIV infection suffered serious adverse events as a result of YF vaccination.Authors' conclusionsYF vaccination can produce protective levels of neutralising antibodies in HIV patients. Immunogenicity of YF vaccine is slightly less in HIV-infected patients compared to HIV-uninfected patients. No serious adverse events related to YF vaccine were observed in HIV-infected study participants. At time of immunisation, higher CD4 cell counts and lower HIV RNA levels in patients with HIV infection seem to be key determinants for development of protective titres of neutralising antibodies. The quality of the evidence for all outcomes was low to very low. YF vaccine may potentially be used safely in HIV-infected patients, although our conclusions are limited by small numbers of patients who have been reported. To assure maximum effectiveness YF vaccine should be given to HIV-infected patients after HIV replication has been suppressed.

Purpose: To report the manifestation of Vogt-Koyanagi-Harada-like disease (VKH) following yellow fever vaccination.Methods: Case report.Results: A 34-year-old immunocompetent male had tinnitus, headache, and decreased vision after a booster dose of yellow fever vaccine. Visual acuity was 20/100 in the right eye and 20/80 in the left, with serous retinal detachment (SRD) and choroidal thickening identified on clinical examination and multimodal imaging. Lumbar puncture revealed pleocytosis and an increased protein content, but extensive investigations ruled out infectious/neurological diseases. Pulse intravenous methylprednisolone was given, followed by a tapering regimen of high-dose oral prednisone. Azathioprine was started early, 3 weeks after initiation of oral steroids. Intraocular inflammation and SRD rapidly resolved, with visual acuity reaching 20/20 in both eyes, after 3 weeks. No recurrence of intraocular inflammation or sign of depigmentation was so far noticed, at 2 years of follow-up.Conclusion: Yellow fever vaccine may be a possible trigger for VKH. [ABSTRACT FROM AUTHOR]

This observational retrospective study conducted during an yellow fever (YF) outbreak in Sao Paulo, Brazil, in 2017-2018, describes adverse events (AE) following YF vaccination of immunocompromised persons. Risks and benefits of vaccination were individually evaluated by physicians. AE were assessed by phone call or electronic mail, 14 to 90 days after vaccination. Three hundred and eighty one immunocompromised persons received a full-dose of YF vaccine. Their age ranged from 1.4 to 89.3 years (median 50.8 years); 53% were women; 178 (46.7%) had chronic kidney disease, 78 (20.5%) had immune-mediated inflammatory diseases; 94 (24.7%) were using or had recently used immunosuppressive/immunomodulatory drugs. All of them denied previous YF vaccination. We were able to contact 341 (89.5%) vaccinees: 233 (68.3%) of them received the YF vaccine from BioManguinhos and 108 (31.7%) received the vaccine from Sanofi-Pasteur; 130 (38.1%) vaccinees received other vaccines (up to 4) simultaneously with the the YF vaccine, mostly hepatitis B (59 vaccinees), pneumococcal polysaccharide 23-valent (46), influenza (43) and diphtheria-tetanus (dT, 41). One hundred and eleven vaccinees (32.6%) reported at least one AE: 79 (23.2%) presented systemic AE, 44 (12.9%) had local AE and 12 had both, local and systemic AE. The most common AE was pain at the injection site (41 persons, 12%), myalgia (34; 10%), fever (25; 7.3%) and headache (16; 4.7%). There was no statistically significant difference on the AE frequency according to the vaccine producer. There were four severe AE: one hospitalization and three deaths, considered not related to the YF vaccine. [ABSTRACT FROM AUTHOR]