A Practical Guide to Full Value of Vaccine Assessments

Articulating the wide range of health, social and economic benefits that vaccines offer may help to overcome obstacles in the vaccine development pipeline. A framework to guide the assessment and communication of the value of a vaccine-the Full Value of Vaccine Assessment (FVVA)-has been developed by the WHO. The FVVA framework offers a holistic assessment of the value of vaccines, providing a synthesis of evidence to inform the public health need of a vaccine, describing the supply and demand aspects, its market and its impact from a health, financial and economic perspective. This paper provides a practical guide to how FVVAs are developed and used to support investment in vaccines, ultimately leading to sustained implementation in countries. The FVVA includes a range of elements that can be broadly categorised as synthesis, vaccine development narrative and defining vaccine impact and value. Depending on the features of the disease/vaccine in question, different elements may be emphasised; however, a standardised set of elements is recommended for each FVVA. The FVVA should be developed by an expert group who represent a range of stakeholders, perspectives and geographies and ensure a fair, coherent and evidence-based assessment of vaccine value.

Immunogenicity and safety of fractional doses of 17D-213 yellow fever vaccine in children (YEFE): a randomised, double-blind, non-inferiority substudy of a phase 4 trial

BACKGROUND

Current supply shortages constrain yellow fever vaccination activities, particularly outbreak response. Although fractional doses of all WHO-prequalified yellow fever vaccines have been shown to be safe and immunogenic in a randomised controlled trial in adults, they have not been evaluated in a randomised controlled trial in young children (9-59 months old). We aimed to assess the immunogenicity and safety of fractional doses compared with standard doses of the WHO-prequalified 17D-213 vaccine in young children.

METHODS

This substudy of the YEFE phase 4 study was conducted at the Epicentre Mbarara Research Centre (Mbarara, Uganda). Eligible children were aged 9-59 months without contraindications for vaccination, without history of previous yellow fever vaccination or infection and not requiring yellow fever vaccination for travelling. Participants were randomly assigned, using block randomisation, 1:1 to standard or fractional (one-fifth) dose of yellow fever vaccine. Investigators, participants, and laboratory personnel were blinded to group allocation. Participants were followed for immunogenicity and safety at 10 days, 28 days, and 1 year after vaccination. The primary outcome was non-inferiority in seroconversion (-10 percentage point margin) 28 days after vaccination measured by 50% plaque reduction neutralisation test (PRNT50) in the per-protocol population. Safety and seroconversion at 10 days and 12-16 months after vaccination (given COVID-19 resctrictions) were secondary outcomes. This study is registered with ClinicalTrials.gov, NCT02991495.

FINDINGS

Between Feb 20, 2019, and Sept 9, 2019, 433 children were assessed, and 420 were randomly assigned to fractional dose (n=210) and to standard dose (n=210) 17D-213 vaccination. 28 days after vaccination, 202 (97%, 95% CI 95-99) of 207 participants in the fractional dose group and 191 (100%, 98-100) of 191 in the standard dose group seroconverted. The absolute difference in seroconversion between the study groups in the per-protocol population was -2 percentage points (95% CI -5 to 1). 154 (73%) of 210 participants in the fractional dose group and 168 (80%) of 210 in the standard dose group reported at least one adverse event 28 days after vaccination. At 10 days follow-up, seroconversion was lower in the fractional dose group than in the standard dose group. The most common adverse events were upper respiratory tract infections (n=221 [53%]), diarrhoea (n=68 [16%]), rhinorrhoea (n=49 [12%]), and conjunctivitis (n=28 [7%]). No difference was observed in incidence of adverse events and serious adverse events between study groups.

CONCLUSIONS

Fractional doses of the 17D-213 vaccine were non-inferior to standard doses in inducing seroconversion 28 days after vaccination in children aged 9-59 months when assessed with PRNT50, but we found fewer children seroconverted at 10 days. The results support consideration of the use of fractional dose of yellow fever vaccines in WHO recommendations for outbreak response in the event of a yellow fever vaccine shortage to include children.

FUNDING

Médecins Sans Frontières Foundation.

The future of Japanese encephalitis vaccination: expert recommendations for achieving and maintaining optimal JE control

Vaccines against Japanese encephalitis (JE) have been available for decades. Currently, most JE-endemic countries have vaccination programs for their at-risk populations. Even so, JE remains the leading recognized cause of viral encephalitis in Asia. In 2018, the U.S. Centers for Disease Control and Prevention and PATH co-convened a group of independent experts to review JE prevention and control successes, identify remaining scientific and operational issues that need to be addressed, discuss opportunities to further strengthen JE vaccination programs, and identify strategies and solutions to ensure sustainability of JE control during the next decade. This paper summarizes the key discussion points and recommendations to sustain and expand JE control.

Evidence-informed vaccination decision-making in countries: Progress, challenges and opportunities

Countries face an increasingly complex vaccination landscape. As well as ever-changing infectious disease epidemiology, the number and diversity of vaccine-preventable diseases, vaccine products, and vaccine technologies continue to increase. To ensure that vaccination decision-making is transparent, country-owned and informed by sound scientific evidence, many countries have established national immunization technical advisory groups (NITAGs) to provide independent expert advice. The past decade has seen substantial growth in NITAG numbers and functionality, and there is now a need to consolidate this progress, by further capacity building, to ensure that NITAGs are responsive to the changing face of immunization over the next decade.

Immunogenicity and safety of fractional doses of yellow fever vaccines: a randomised, double-blind, non-inferiority trial

BACKGROUND

Stocks of yellow fever vaccine are insufficient to cover exceptional demands for outbreak response. Fractional dosing has shown efficacy, but evidence is limited to the 17DD substrain vaccine. We assessed the immunogenicity and safety of one-fifth fractional dose compared with standard dose of four WHO-prequalified yellow fever vaccines produced from three substrains.

METHODS

We did this randomised, double-blind, non-inferiority trial at research centres in Mbarara, Uganda, and Kilifi, Kenya. Eligible participants were aged 18-59 years, had no contraindications for vaccination, were not pregnant or lactating, had no history of yellow fever vaccination or infection, and did not require yellow fever vaccination for travel. Eligible participants were recruited from communities and randomly assigned to one of eight groups, corresponding to the four vaccines at standard or fractional dose. The vaccine was administered subcutaneously by nurses who were not masked to treatment, but participants and other study personnel were masked to vaccine allocation. The primary outcome was proportion of participants with seroconversion 28 days after vaccination. Seroconversion was defined as post-vaccination neutralising antibody titres at least 4 times pre-vaccination measurement measured by 50% plaque reduction neutralisation test (PRNT50). We defined non-inferiority as less than 10% decrease in seroconversion in fractional compared with standard dose groups 28 days after vaccination. The primary outcome was measured in the per-protocol population, and safety analyses included all vaccinated participants. This trial is registered with ClinicalTrials.gov, NCT02991495.

FINDINGS

Between Nov 6, 2017, and Feb 21, 2018, 1029 participants were assessed for inclusion. 69 people were ineligible, and 960 participants were enrolled and randomly assigned to vaccine manufacturer and dose (120 to Bio-Manguinhos-Fiocruz standard dose, 120 to Bio-Manguinhos-Fiocruz fractional dose, 120 to Chumakov Institute of Poliomyelitis and Viral Encephalitides standard dose, 120 to Chumakov Institute of Poliomyelitis and Viral Encephalitides fractional dose, 120 to Institut Pasteur Dakar standard dose, 120 to Institut Pasteur Dakar fractional dose, 120 to Sanofi Pasteur standard dose, and 120 to Sanofi Pasteur fractional dose). 49 participants had detectable PRNT50 at baseline and 11 had missing PRNT50 results at baseline or 28 days. 900 were included in the per-protocol analysis. 959 participants were included in the safety analysis. The absolute difference in seroconversion between fractional and standard doses by vaccine was 1·71% (95% CI -2·60 to 5·28) for Bio-Manguinhos-Fiocruz, -0·90% (-4·24 to 3·13) for Chumakov Institute of Poliomyelitis and Viral Encephalitides, 1·82% (-2·75 to 5·39) for Institut Pasteur Dakar, and 0·0% (-3·32 to 3·29) for Sanofi Pasteur. Fractional doses from all four vaccines met the non-inferiority criterion. The most common treatment-related adverse events were headache (22·2%), fatigue (13·7%), myalgia (13·3%) and self-reported fever (9·0%). There were no study-vaccine related serious adverse events.

INTERPRETATION

Fractional doses of all WHO-prequalified yellow fever vaccines were non-inferior to the standard dose in inducing seroconversion 28 days after vaccination, with no major safety concerns. These results support the use of fractional dosage in the general adult population for outbreak response in situations of vaccine shortage.

FUNDING

The study was funded by Médecins Sans Frontières Foundation, Wellcome Trust (grant no. 092654), and the UK Department for International Development. Vaccines were donated in kind.

Global vaccine action plan lessons learned I: Recommendations for the next decade

The Global Vaccine Action Plan 2011-2020 (GVAP) was developed to realize the ambitions of the Decade of Vaccines - that all individuals and communities enjoy lives free from vaccine-preventable diseases. It included a comprehensive monitoring and evaluation/accountability framework to assess progress towards global targets with recommendations for corrective actions. While many of the GVAP targets are very unlikely to be met by the end of 2020, substantial progress has nevertheless been made, establishing a strong foundation for a successor global immunization strategy, the Immunization Agenda 2030 (IA2030). The Strategic Advisory Group of Experts on immunization has made a series of recommendations to ensure that the lessons learned from GVAP inform the development and implementation of IA2030.

Review of data and knowledge gaps regarding yellow fever vaccine-induced immunity and duration of protection

Yellow fever (YF) virus is a mosquito-borne flavivirus found in Sub-Saharan Africa and tropical South America. The virus causes YF, a viral hemorrhagic fever, which can be prevented by a live-attenuated vaccine, strain 17D. Despite the vaccine being very successful at decreasing disease risk, YF is considered a re-emerging disease due to the increased numbers of cases in the last 30 years. Until 2014, the vaccine was recommended to be administered with boosters every 10 years, but in 2014 the World Health Organization recommended removal of booster doses for all except special populations. This recommendation has been questioned and there have been reports of waning antibody titers in adults over time and more recently in pediatric populations. Clearly, the potential of waning antibody titers is a very important issue that needs to be carefully evaluated. In this Perspective, we review what is known about the correlate of protection for full-dose YF vaccine, current information on waning antibody titers, and gaps in knowledge. Overall, fundamental questions exist on the durability of protective immunity induced by YF vaccine, but interpretation of studies is complicated by the use of different assays and different cut-offs to measure seroprotective immunity, and differing results among certain endemic versus non-endemic populations. Notwithstanding the above, there are few well-characterized reports of vaccine failures, which one would expect to observe potentially more with the re-emergence of a severe disease. Overall, there is a need to improve YF disease surveillance, increase primary vaccination coverage rates in at-risk populations, and expand our understanding of the mechanism of protection of YF vaccine.

Antenatal care service delivery and factors affecting effective tetanus vaccine coverage in low- and middle-income countries: Results of the Maternal Immunisation and Antenatal Care Situational analysis (MIACSA) project

Objectives

To map the integration of existing maternal tetanus immunization programmes within antenatal care (ANC) services for pregnant women in low- and middle-income countries (LMICs) and to identify and understand the challenges, barriers and facilitators associated with high performance maternal vaccine service delivery.

Design

A mixed methods, cross sectional study with four data collection phases including a desk review, online survey, telephone and face-to-face interviews and in country visits was undertaken between 2016 and 2018. Associations of different service delivery process components with protection at birth (PAB) and with country groups were established. PAB was defined as the proportion of neonates protected at birth against neonatal tetanus. Regression analysis and structural equation modelling was used to assess associations of different variables with maternal tetanus immunization coverage. Latent class analysis (LCA), was used to group country performance for maternal immunization, and to address the problem of multicollinearity.

Setting

LMICs.

Results

The majority of LMICs had a policy on recommended number of ANC visits, however most were yet to implement the WHO guidelines recommending eight ANC contacts. Countries that recommended > 4 ANC contacts were more likely to have high PAB > 90%. Passive disease surveillance was the most common form of disease surveillance performed but the maternal and neonatal morbidity and mortality indicators recorded differed between countries. The presence of user fees for antenatal care and maternal immunization was significantly associated with lower PAB (<90%).

Conclusions

Recommendations include implementing the current WHO ANC guideline to facilitate increased opportunities for vaccination during each pregnancy. Improved utilisation of ANC services by increasing the demand side by increasing the quality of services, reducing any associated costs and supporting user fee exemptions, or the supply side can also enhance utilisation of ANC services which are positioned as an ideal platform for delivery of maternal vaccines.

Revised Global Typhoid Vaccination Policy

Typhoid fever is a continuing public health problem in many low- and middle-income countries; however, routine vaccination as a recommended control strategy has not been implemented in the past in most countries. Greater understanding of the typhoid fever burden, the increasing threat of antimicrobial resistance, and licensure of a new generation of typhoid conjugate vaccines (TCVs) were instrumental in paving the way for the World Health Organization (WHO) to issue a revised global policy on typhoid vaccines in March 2018. The new policy follows evidence-based recommendations by the WHO Strategic Advisory Group of Experts on immunization for routine and catch-up vaccination with TCVs and highlights considerations for universal, risk-based, or phased vaccination strategies in different settings. Further, the first WHO-prequalified TCV and Gavi funding for eligible countries make vaccination a realistic control strategy for many affected countries, especially if combined with improved water and sanitation services, strengthened surveillance systems, and appropriate antimicrobial treatment.

Closer and closer? Maternal immunization: current promise, future horizons

This state-of-the art manuscript highlights our current understanding of maternal immunization-the practice of vaccinating pregnant women to confer protection on them as well as on their young infants, and thereby reduce vaccine-preventable morbidity and mortality. Advances in our understanding of the immunologic processes that undergird a normal pregnancy, studies from vaccines currently available and recommended for pregnant women, and vaccines for administration in special situations are beginning to build the case for safe scale-up of maternal immunization. In addition to well-known diseases, new diseases are emerging which pose threats. Several new vaccines are currently under development and increasingly include pregnant women. In this manuscript, targeted at clinicians, vaccinologists, scientists, public health practitioners, and policymakers, we also outline key considerations around maternal immunization introduction and delivery, discuss noninfectious horizons for maternal immunization, and provide a framework for the clinician faced with immunizing a pregnant woman.

Determining the Best Immunization Strategy for Protecting African Children Against Invasive Salmonella Disease

Background

The World Health Organization recently prequalified a typhoid conjugate vaccine (TCV), recommending its use in persons ≥6 months to 45 years residing in typhoid fever (TF)-endemic areas. We now need to consider how TCVs can have the greatest impact in the most vulnerable populations.

Methods

The Typhoid Fever Surveillance in Africa Program (TSAP) was a blood culture-based surveillance of febrile patients from defined populations presenting at healthcare facilities in 10 African countries. TF and invasive non-typhoidal Salmonella (iNTS) disease incidences were estimated for 0-10 year-olds in one-year age increments.

Results

Salmonella Typhi and iNTS were the most frequently isolated pathogens; 135 and 94 cases were identified, respectively. Analysis from three countries was excluded (incomplete person-years of observation (PYO) data). Thirty-seven of 123 TF cases (30.1%) and 71/90 iNTS disease cases (78.9%) occurred in children aged <5 years. No TF and 8/90 iNTS infections (8.9%) were observed in infants aged <9 months. The TF incidences (/100 000 PYO) for children aged <1 year and 1 to <2 years were 5 and 39, respectively; the highest incidence was 304 per 100 000 PYO in 4 to <5 year-olds. The iNTS disease incidence in the defined age groups ranged between 81 and 233 per 100 000 PYO, highest in 1 to <2 year-olds. TF and iNTS disease incidences were higher in West Africa.

Conclusions

High burden of TF detected in young children strengthens the need for TCV introduction. Given the concurrent iNTS disease burden, development of a trivalent vaccine against S. Typhi, S. Typhimurium, and S. Enteritidis may be timely in this region.

Estimating the proportion of vaccine-induced hospitalized dengue cases among Dengvaxia vaccinees in the Philippines

Background: Dengvaxia was used in the Philippines to vaccinate 9-10-year-old school children, living in areas highly endemic for dengue. After about 830,000 had received at least 1 of 3 recommended doses, risks of enhanced disease in dengue-naïve vaccinees were reported. Methods: We used Phase 3 trial data to derive the proportions of cases of hospitalised and severe dengue that might have been prevented by the Philippines vaccination programme and, among those cases that may occur in vaccinees, what proportions are likely to arise in those who were seropositive or seronegative for dengue at the time of first vaccination and what proportion in the latter group may be enhanced disease attributable to the vaccine. Results: Assuming about 15% of vaccinees were dengue naïve at vaccination and the effects of the vaccine are independent of the number of doses received, we estimate that, in the 5 years following vaccination, the number of cases of severe disease in the vaccinated population will be reduced by about 70%. Among vaccinees who do develop severe disease, about half the cases will be due to vaccine breakthrough in seropositive vaccinees, and about a quarter will be excess cases in seronegative vaccinees that will have occurred as a consequence of vaccination. Conclusions: Overall, the Philippine dengue vaccination programme will likely prevent a substantial number of severe dengue cases and, among those that do occur, the majority are likely to be breakthrough disease in seropositive vaccinees and a minority attributable to the excess risk of enhanced disease in seronegative vaccinees.

Maternal immunization in Malawi: A mixed methods study of community perceptions, programmatic considerations, and recommendations for future planning

BACKGROUND

Safe, effective vaccines are given to pregnant women to protect their infants and/or themselves against certain infectious agents; however, apart from tetanus vaccination, maternal immunization in low- and middle-income countries (LMICs) remains low. Tetanus toxoid vaccine is integrated into antenatal care services in Malawi with high coverage and provides an opportunity to identify factors that facilitate successful immunization delivery to pregnant women in LMICs.

METHODS

PATH and the University of Malawi's Centre for Social Research conducted a mixed-methods study in 2015 to document community perceptions of maternal immunization, using tetanus vaccine as an example, and to identify factors perceived to be important to successfully introducing other maternal vaccines, such as influenza vaccine, in Malawi. We conducted 18 focus group discussions with pregnant and recently pregnant women and their family members and 76 semi-structured interviews with pregnant and recently pregnant women, community leaders, health workers, public health program managers, non-governmental partners, and policy makers.

RESULTS

We identified factors perceived to support the introduction of new maternal vaccines, including strong maternal vaccine acceptance in the community, an existing strategy for maternal tetanus vaccine delivery, and positive health workers' views about the introduction of additional maternal vaccines. Potential challenges to adoption and acceptance included identifying and tracking the target population and monitoring adverse events, and the need to ensure operational capacity of the health system to support the introduction and wide-scale use of an additional vaccine. For influenza vaccine specifically, additional challenges included limited awareness of influenza disease and its low prioritization among health needs.

CONCLUSIONS

Lessons from the successful delivery of maternal tetanus immunization in Malawi may be informative for similar countries considering new vaccines for pregnant women or striving to optimize the delivery of those currently provided.

Maternal Immunization and Antenatal Care Situation Analysis (MIACSA) study protocol: a multiregional, cross-sectional analysis of maternal immunization delivery strategies to reduce maternal and neonatal morbidity and mortality

INTRODUCTION

Maternal immunization (MI) with tetanus toxoid containing vaccine, is a safe and cost-effective way of preventing neonatal tetanus. Given the prospect of introducing new maternal vaccines in the near future, it is essential to identify and understand current policies, practices and unmet needs for introducing and/or scaling up MI in low-income and middle-income countries (LMICs).

METHODS AND ANALYSIS

The Maternal Immunization and Antenatal Care Situation Analysis (MIACSA) is a mixed methods, cross-sectional study that will collect data in four phases: (1) a review of global databases for selected health indicators in 136 LMICs; (2) a structured online survey directed at Maternal, Newborn and Child Health and Expanded Programme on Immunization focal points in all 136 LMICs; (3) semistructured telephone interviews of 30 selected LMICs and (4) 10 week-long country visits, including key informant interviews, health facility visits and focus group discussions. The principal analyses will assess correlations between the various aspects of MI delivery strategies and proxy measures of health systems performance related to vaccine-preventable disease control. The primary outcome will be a typology of existing MI delivery models, and secondary outcomes will include country profiles of child and maternal health indicators, and a MI gaps and needs analysis.

ETHICS AND DISSEMINATION

The protocol was approved by the WHO Ethics Review Committee (ERC.0002908). The results will be made available in a project report and submitted for publication in peer-reviewed journals that will be shared broadly among global health decision-makers, researchers, product developers and country-level stakeholders.

Demonstrating vaccine effectiveness during a waning epidemic: A WHO/NIH meeting report on approaches to development and licensure of Zika vaccine candidates

Since its peak in early 2016, the incidence of Zika virus (ZIKV) cases has declined to such low levels that Phase 3 field efficacy trials may be infeasible. While great progress was made to rapidly advance several vaccine candidates into Phase 1 and 2 clinical trials, in the absence of sustained viral transmission it may be difficult to evaluate the effectiveness of ZIKV vaccine candidates by conducting traditional clinical disease endpoint efficacy studies. However, ZIKV is still circulating at low levels in some areas and is likely to re-emerge in naïve populations or in sites of prior epidemics once population immunity wanes. Therefore, the public health need for a ZIKV vaccine remains. To facilitate continued ZIKV vaccine development efforts, the World Health Organization's Initiative for Vaccine Research and the National Institutes of Health's National Institute of Allergy and Infectious Diseases co-hosted a meeting of experts in March 2018 to identify strategies to demonstrate vaccine effectiveness in view of waning ZIKV disease incidence. This paper outlines points for consideration for developers, regulators, and other stakeholders working towards a licensed ZIKV vaccine. These deliberations may also be applicable to development of vaccines for other emerging infections where the size, unpredictability, and ephemeral nature of outbreaks makes clinical disease endpoint efficacy trials to demonstrate vaccine effectiveness infeasible.

Clinical development and regulatory points for consideration for second-generation live attenuated dengue vaccines

Licensing and decisions on public health use of a vaccine rely on a robust clinical development program that permits a risk-benefit assessment of the product in the target population. Studies undertaken early in clinical development, as well as well-designed pivotal trials, allow for this robust characterization. In 2012, WHO published guidelines on the quality, safety and efficacy of live attenuated dengue tetravalent vaccines. Subsequently, efficacy and longer-term follow-up data have become available from two Phase 3 trials of a dengue vaccine, conducted in parallel, and the vaccine was licensed in December 2015. The findings and interpretation of the results from these trials released both before and after licensure have highlighted key complexities for tetravalent dengue vaccines, including concerns vaccination could increase the incidence of dengue disease in certain subpopulations. This report summarizes clinical and regulatory points for consideration that may guide vaccine developers on some aspects of trial design and facilitate regulatory review to enable broader public health recommendations for second-generation dengue vaccines.

Zika vaccines and therapeutics: landscape analysis and challenges ahead

BACKGROUND

Various Zika virus (ZIKV) vaccine candidates are currently in development. Nevertheless, unique challenges in clinical development and regulatory pathways may hinder the licensure of high-quality, safe, and effective ZIKV vaccines.

DISCUSSION

Implementing phase 3 efficacy trials will be difficult given the challenges of the spatio-temporal heterogeneity of ZIKV transmission, the unpredictability of ZIKV epidemics, the broad spectrum of clinical manifestations making a single definite endpoint difficult, a lack of sensitive and specific diagnostic assays, and the need for inclusion of vulnerable target populations. In addition to a vaccine, drugs for primary prophylaxis, post-exposure prophylaxis, or treatment should also be developed to prevent or mitigate the severity of congenital Zika syndrome.

CONCLUSION

Establishing the feasibility of immune correlates and/or surrogates are a priority. Given the challenges in conducting phase 3 trials at a time of waning incidence, human challenge trials should be considered to evaluate efficacy. Continued financial support and engagement of industry partners will be essential to the successful development, licensure, and accessibility of Zika vaccines or therapeutics.

Live-attenuated tetravalent dengue vaccines: The needs and challenges of post-licensure evaluation of vaccine safety and effectiveness

Since December 2015, the first dengue vaccine has been licensed in several Asian and Latin American countries for protection against disease from all four dengue virus serotypes. While the vaccine demonstrated an overall good safety and efficacy profile in clinical trials, some key research questions remain which make risk-benefit-assessment for some populations difficult. As for any new vaccine, several questions, such as very rare adverse events following immunization, duration of vaccine-induced protection and effectiveness when used in public health programs, will be addressed by post-licensure studies and by data from national surveillance systems after the vaccine has been introduced. However, the complexity of dengue epidemiology, pathogenesis and population immunity, as well as some characteristics of the currently licensed vaccine, and potentially also future, live-attenuated dengue vaccines, poses a challenge for evaluation through existing monitoring systems, especially in low and middle-income countries. Most notable are the different efficacies of the currently licensed vaccine by dengue serostatus at time of first vaccination and by dengue virus serotype, as well as the increased risk of dengue hospitalization among young vaccinated children observed three years after the start of vaccination in one of the trials. Currently, it is unknown if the last phenomenon is restricted to younger ages or could affect also seronegative individuals aged 9years and older, who are included in the group for whom the vaccine has been licensed. In this paper, we summarize scientific and methodological considerations for public health surveillance and targeted post-licensure studies to address some key research questions related to live-attenuated dengue vaccines. Countries intending to introduce a dengue vaccine should assess their capacities to monitor and evaluate the vaccine's effectiveness and safety and, where appropriate and possible, enhance their surveillance systems accordingly. Targeted studies are needed, especially to better understand the effects of vaccinating seronegative individuals.

Respiratory syncytial virus vaccine research and development: World Health Organization technological roadmap and preferred product characteristics

The respiratory syncytial virus causes a considerable respiratory disease burden globally, most markedly in young infants, in low and middle income countries. A diverse product pipeline illustrates the recent intensification of research and development activities for vaccines and monoclonal antibodies against RSV. With the aim to ensure that product development activities are directed to address the public health needs, the World Health Organization has developed a research and development technical roadmap and articulated product characteristics preferences.

Meeting report: Global vaccine and immunization research forum

Building on the success of the first Global Vaccine and Immunization Research Forum (GVIRF), the World Health Organization, the National Institute of Allergy and Infectious Diseases, part of the National Institutes of Health in the United States of America, and the Bill & Melinda Gates Foundation convened the second GVIRF in March 2016. Leading scientists, vaccine developers, and public health officials from around the world discussed scientific advances and innovative technologies to design and deliver vaccines as well as novel tools and approaches to increase the uptake of vaccines throughout the world. This report summarizes the discussions and conclusions from the forum participants.

Report on eighth WHO meeting on development of influenza vaccines that induce broadly protective and long-lasting immune responses: Chicago, USA, 23-24 August 2016

In August 2016, the World Health Organization (WHO) convened the "Eighth meeting on development of influenza vaccines that induce broadly protective and long-lasting immune responses" to discuss the regulatory requirements and pathways for licensure of next-generation influenza vaccines, and to identify areas where WHO can promote the development of such vaccines. Participants included approximately 120 representatives of academia, the vaccine industry, research and development funders, and regulatory and public health agencies. They reviewed the draft WHO preferred product characteristics (PPCs) of vaccines that could address prioritized unmet public health needs and discussed the challenges facing the development of such vaccines, especially for low- and middle-income countries (LMIC). They defined the data desired by public-health decision makers globally and explored how to support the progression of promising candidates into late-stage clinical trials and for all countries. This report highlights the major discussions of the meeting.

Global yellow fever vaccination coverage from 1970 to 2016: an adjusted retrospective analysis

Background

Substantial outbreaks of yellow fever in Angola and Brazil in the past 2 years, combined with global shortages in vaccine stockpiles, highlight a pressing need to assess present control strategies. The aims of this study were to estimate global yellow fever vaccination coverage from 1970 through to 2016 at high spatial resolution and to calculate the number of individuals still requiring vaccination to reach population coverage thresholds for outbreak prevention.

Methods

For this adjusted retrospective analysis, we compiled data from a range of sources (eg, WHO reports and health-service-provider registeries) reporting on yellow fever vaccination activities between May 1, 1939, and Oct 29, 2016. To account for uncertainty in how vaccine campaigns were targeted, we calculated three population coverage values to encompass alternative scenarios. We combined these data with demographic information and tracked vaccination coverage through time to estimate the proportion of the population who had ever received a yellow fever vaccine for each second level administrative division across countries at risk of yellow fever virus transmission from 1970 to 2016.

Findings

Overall, substantial increases in vaccine coverage have occurred since 1970, but notable gaps still exist in contemporary coverage within yellow fever risk zones. We estimate that between 393·7 million and 472·9 million people still require vaccination in areas at risk of yellow fever virus transmission to achieve the 80% population coverage threshold recommended by WHO; this represents between 43% and 52% of the population within yellow fever risk zones, compared with between 66% and 76% of the population who would have required vaccination in 1970.

Interpretation

Our results highlight important gaps in yellow fever vaccination coverage, can contribute to improved quantification of outbreak risk, and help to guide planning of future vaccination efforts and emergency stockpiling.

Funding

The Rhodes Trust, Bill & Melinda Gates Foundation, the Wellcome Trust, the National Library of Medicine of the National Institutes of Health, the European Union's Horizon 2020 research and innovation programme.

What Have We Learned From the Typhoid Fever Surveillance in Africa Program?

The Typhoid Fever Surveillance in Africa Program (TSAP) was established in 2009 to fill the data void concerning invasive Salmonella disease in sub-Saharan Africa, and to specifically estimate the burden of bloodstream infections caused by the key pathogen, Salmonella enterica serovar Typhi. TSAP has achieved this ambitious target, finding high incidences of typhoid fever in both rural and urban populations in several countries in sub-Saharan Africa. The results of TSAP will undoubtedly dictate the direction of future typhoid fever research in Africa, and at last provides a key piece of the disease burden jigsaw puzzle. With the dawn of new Vi conjugate vaccines against Salmonella Typhi, the next priority for the typhoid community must be providing the required data on these vaccines so they can be licensed and provided to those in high-risk groups and locations across sub-Saharan Africa.

Developing a vaccine against Zika

We’ve made a good start but substantial challenges remain

A global review of national influenza immunization policies: Analysis of the 2014 WHO/UNICEF Joint Reporting Form on immunization

Introduction

The WHO recommends annual influenza vaccination to prevent influenza illness in high-risk groups. Little is known about national influenza immunization policies globally.

Material and Methods

The 2014 WHO/UNICEF Joint Reporting Form (JRF) on Immunization was adapted to capture data on influenza immunization policies. We combined this dataset with additional JRF information on new vaccine introductions and strength of immunization programmes, as well as publicly available data on country economic status. Data from countries that did not complete the JRF were sought through additional sources. We described data on country influenza immunization policies and used bivariate analyses to identify factors associated with having such policies.

Results

Of 194 WHO Member States, 115 (59%) reported having a national influenza immunization policy in 2014. Among countries with a national policy, programmes target specific WHO-defined risk groups, including pregnant women (42%), young children (28%), adults with chronic illnesses (46%), the elderly (45%), and health care workers (47%). The Americas, Europe, and Western Pacific were the WHO regions that had the highest percentages of countries reporting that they had national influenza immunization policies. Compared to countries without policies, countries with policies were significantly more likely to have the following characteristics: to be high or upper middle income (p < 0.0001); to have introduced birth dose hepatitis B virus vaccine (p < 0.0001), pneumococcal conjugate vaccine (p = 0.032), or human papilloma virus vaccine (p = 0.002); to have achieved global goals for diphtheria-tetanus-pertussis vaccine coverage (p < 0.0001); and to have a functioning National Immunization Technical Advisory Group (p < 0.0001).

Conclusions

The 2014 revision of the JRF permitted a global assessment of national influenza immunization policies. The 59% of countries reporting that they had policies are wealthier, use more new or under-utilized vaccines, and have stronger immunization systems. Addressing disparities in public health resources and strengthening immunization systems may facilitate influenza vaccine introduction and use.

Review of prescribing information for influenza vaccines for pregnant and lactating women

Information provided by most influenza vaccine manufacturers do not reflect the recommendations of WHO and/or national public health advisory groups with regard to the use of influenza vaccines in pregnant or lactating women. The majority of vaccines contain precautionary language which could discourage use in pregnant women and some include stronger language discouraging or contradicting use in pregnant or lactating women. Regulators and manufacturers should regularly assess the language of pregnancy and lactation sections in product information for vaccines and include information from national public health advisory groups regarding use by pregnant or lactating women and data from relevant studies.

Research and development of Zika virus vaccines

Zika virus (ZIKV) is a member of the family Flaviviridae, genus Flavivirus, and is transmitted by Aedes sp. mosquitoes. There are three genetic lineages of ZIKV: the East African, West African and Asian lineages. Until recently, Zika fever (ZF) has normally been considered a rare, mild febrile disease, but reports since 2012 have shown potentially severe complications associated with ZIKV infection, including microcephaly and Guillain-Barré syndrome. There are no licensed vaccines for ZIKV; however, many vaccine platforms/approaches that have been utilised for other flavivirus vaccines are being applied to ZIKV. Given the current outbreak of ZIKV in the Americas with its associated risks to pregnancy, we summarise what is known about the virus, how knowledge of currently licensed flavivirus vaccines can be applied to ZIKV vaccine development and the assessments of potential challenges for ZIKV vaccine testing and evaluation.

Report on the second WHO integrated meeting on development and clinical trials of influenza vaccines that induce broadly protective and long-lasting immune responses: Geneva, Switzerland, 5-7 May 2014

On 5-7 May 2014, the World Health Organization (WHO) convened the second integrated meeting on "influenza vaccines that induce broadly protective and long-lasting immune responses". Around 100 invited experts from academia, the vaccine industry, research and development funders, and regulatory and public health agencies attended the meeting. Areas covered included mechanisms of protection in natural influenza-virus infection and vaccine-induced immunity, new approaches to influenza-vaccine design and production, and novel routes of vaccine administration. A timely focus was on how this knowledge could be applied to both seasonal influenza and emerging viruses with pandemic potential such as influenza A (H7N9), currently circulating in China. Special attention was given to the development of possible universal influenza vaccines, given that the Global Vaccine Action Plan calls for at least one licensed universal influenza vaccine by 2020. This report highlights some of the topics discussed and provides an update on studies published since the report of the previous meeting.

Global Vaccine and Immunization Research Forum: Opportunities and challenges in vaccine discovery, development, and delivery

The World Health Organization, the National Institute of Allergy and Infectious Diseases, part of the National Institutes of Health, and the Bill & Melinda Gates Foundation convened the first Global Vaccine and Immunization Research Forum (GVIRF) in March 2014. This first GVIRF aimed to track recent progress of the Global Vaccine Action Plan research and development agenda, identify opportunities and challenges, promote partnerships in vaccine research, and facilitate the inclusion of all stakeholders in vaccine research and development. Leading scientists, vaccine developers, and public health officials from around the world discussed scientific and technical challenges in vaccine development, research to improve the impact of immunization, and regulatory issues. This report summarizes the discussions and conclusions from the forum participants.

Next generation dengue vaccines: A review of the preclinical development pipeline

Dengue represents a significant and growing public health problem across the globe, with approximately half of the world's population at risk. The increasing and expanding burden of dengue has highlighted the need for new tools to prevent dengue, including development of dengue vaccines. Recently, the first dengue vaccine candidate was evaluated in Phase 3 clinical trials, and other vaccine candidates are under clinical evaluation. There are also a number of candidates in preclinical development, based on diverse technologies, with promising results in animal models and likely to move into clinical trials and could eventually be next-generation dengue vaccines. This review provides an overview of the various technological approaches to dengue vaccine development with specific focus on candidates in preclinical development and with evaluation in non-human primates.

Gender Determinants of Vaccination Status in Children: Evidence from a Meta-Ethnographic Systematic Review

Using meta-ethnographic methods, we conducted a systematic review of qualitative research to understand gender-related reasons at individual, family, community and health facility levels why millions of children in low and middle income countries are still not reached by routine vaccination programmes. A systematic search of Medline, Embase, CINAHL, Cochrane Library, ERIC, Anthropological Lit, CSA databases, IBSS, ISI Web of Knowledge, JSTOR, Soc Index and Sociological Abstracts was conducted. Key words were built around the themes of immunization, vaccines, health services, health behaviour, and developing countries. Only papers, which reported on in-depth qualitative data, were retained. Twenty-five qualitative studies, which investigated barriers to routine immunisation, were included in the review. These studies were conducted between 1982 and 2012; eighteen were published after 2000. The studies represent a wide range of low- to middle income countries including some that have well known coverage challenges. We found that women's low social status manifests on every level as a barrier to accessing vaccinations: access to education, income, as well as autonomous decision-making about time and resource allocation were evident barriers. Indirectly, women's lower status made them vulnerable to blame and shame in case of childhood illness, partly reinforcing access problems, but partly increasing women's motivation to use every means to keep their children healthy. Yet in settings where gender discrimination exists most strongly, increasing availability and information may not be enough to reach the under immunised. Programmes must actively be designed to include mitigation measures to facilitate women's access to immunisation services if we hope to improve immunisation coverage. Gender inequality needs to be addressed on structural, community and household levels if the number of unvaccinated children is to substantially decrease.

Long-term safety assessment of live attenuated tetravalent dengue vaccines: deliberations from a WHO technical consultation

Dengue is a rapidly growing public health threat with approximately 2.5 billion people estimated to be at risk. Several vaccine candidates are at various stages of pre-clinical and clinical development. Thus far, live dengue vaccine candidates have been administered to several thousands of volunteers and were well-tolerated, with minimal short-term safety effects reported in Phase I and Phase II clinical trials. Based on the natural history of dengue, a theoretical possibility of an increased risk of severe dengue as a consequence of vaccination has been hypothesized but not yet observed. In October 2011, the World Health Organization (WHO) convened a consultation of experts in dengue, vaccine regulation and vaccine safety to review the current scientific evidence regarding safety concerns associated with live attenuated dengue vaccines and, in particular, to consider methodological approaches for their long-term evaluation. In this paper we summarize the scientific background and methodological considerations relevant to the safety assessment of these vaccines. Careful planning and a coordinated approach to safety assessment are recommended to ensure adequate long-term evaluation of dengue vaccines that will support their introduction and continued use.

Vaccines and vaccination against tick-borne encephalitis

Tick-borne encephalitis (TBE) is an emerging viral zoonosis and is endemic from Japan, China, Mongolia and Russia, to Central Europe and France. There is no specific treatment and TBE can be fatal. The four licensed prophylactic vaccines are produced according to WHO manufacturing requirements. Large clinical trials and postmarketing surveillance demonstrated safety and efficacy of the two European vaccines. The two Russian vaccines showed their effectiveness in daily use, but limited published data are available on controlled clinical trials. Vaccination recommendations in endemic areas vary significantly. In some countries, public vaccination programs are implemented. The WHO has recently issued recommendations on evidence-based use of TBE vaccines. However, more data are needed regarding safety, efficacy and long-term protection after vaccination.