Last data update: May 20, 2024. (Total: 46824 publications since 2009)
Records 1-12 (of 12 Records) |
Query Trace: Hombach J[original query] |
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The future of Japanese encephalitis vaccination: expert recommendations for achieving and maintaining optimal JE control
Vannice KS , Hills SL , Schwartz LM , Barrett AD , Heffelfinger J , Hombach J , Letson GW , Solomon T , Marfin AA . NPJ Vaccines 2021 6 (1) 82 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. |
Review of data and knowledge gaps regarding yellow fever vaccine-induced immunity and duration of protection
Staples JE , Barrett ADT , Wilder-Smith A , Hombach J . NPJ Vaccines 2020 5 (1) 54 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. |
Global vaccine action plan lessons learned I: Recommendations for the next decade
MacDonald N , Mohsni E , Al-Mazrou Y , Kim Andrus J , Arora N , Elden S , Madrid MY , Martin R , Mahmoud Mustafa A , Rees H , Salisbury D , Zhao Q , Jones I , Steffen CA , Hombach J , O'Brien KL , Cravioto A . Vaccine 2020 38 (33) 5364-5371 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. |
Differences between coverage of yellow fever vaccine and the first dose of measles-containing vaccine: A desk review of global data sources
Adrien N , Hyde TB , Gacic-Dobo M , Hombach J , Krishnaswamy A , Lambach P . Vaccine 2019 37 (32) 4511-4517 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. |
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
Ortiz JR , Hickling J , Jones R , Donabedian A , Engelhardt OG , Katz JM , Madhi SA , Neuzil KM , Rimmelzwaan GF , Southern J , Spiro DJ , Hombach J . Vaccine 2017 36 (7) 932-938 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. |
Quantifying the epidemiological impact of vector control on dengue
Reiner RC Jr , Achee N , Barrera R , Burkot TR , Chadee DD , Devine GJ , Endy T , Gubler D , Hombach J , Kleinschmidt I , Lenhart A , Lindsay SW , Longini I , Mondy M , Morrison AC , Perkins TA , Vazquez-Prokopec G , Reiter P , Ritchie SA , Smith DL , Strickman D , Scott TW . PLoS Negl Trop Dis 2016 10 (5) e0004588 Dengue virus (DENV) is a self-limiting illness in tropical and subtropical regions around the globe caused by four closely related, but distinct, virus serotypes (DENV-1, -2, -3, and -4) that are transmitted among humans by mosquitoes, primarily Aedes aegypti [1]. Approximately 4 billion people living in more than 128 countries are at risk of infection [2]. Each year there are an estimated 400 million new infections, of which about 100 million manifest as apparent illness [3]. The outcome of human infections ranges from asymptomatic to mild illness to severe, life-threatening disease [4]. DENV not only causes more human morbidity and mortality than any other arthropod-borne virus but it is also a growing public health threat. There has been a dramatic 4-fold increase in dengue cases between 1990–2013 and dengue continues to expand in geographic range [2,3,5,6]. | Presently, vector control is the primary means for preventing dengue [7]. Several vaccine constructs are in clinical trials and initial results are encouraging [8]; recently licensure was granted for the Sanofi Pasteur vaccine in Mexico, Brazil, and the Philippines [9]. A few well-documented successes indicate that, when rigorously applied, vector control can reduce dengue. The advent of DDT in 1947 led to a hemisphere-wide program in the 1950s and 1960s across Central and South America that dramatically reduced Ae. aegypti populations, resulting in impressive reductions in yellow fever and dengue [10]. During the 1970s–1980s [11] and the 1980s–1990s [12], respectively, Singapore and Cuba successfully used vector control and larval source reduction to reduce the force of DENV infection (i.e., per capita risk of human infection [13]) and, thus, disease. Recent trials of indoor residual spraying [14] and indoor space spraying [15] appeared to reduce human DENV infections. Regrettably, these control achievements were rare and ultimately transient. Dengue reinvaded Latin America after the Ae. aegypti eradication campaign ended, rebounded in Singapore and Cuba after 20 and 16 years of successful control, respectively, and is increasingly being reported in Africa due to improved surveillance [16]. |
Long-term safety assessment of live attenuated tetravalent dengue vaccines: deliberations from a WHO technical consultation
Bentsi-Enchill AD , Schmitz J , Edelman R , Durbin A , Roehrig JT , Smith PG , Hombach J , Farrar J . Vaccine 2013 31 (23) 2603-9 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. |
Estimated global incidence of Japanese encephalitis: a systematic review
Campbell GL , Hills SL , Fischer M , Jacobson JA , Hoke CH , Hombach JM , Marfin AA , Solomon T , Tsai TF , Tsu VD , Ginsburg AS . Bull World Health Organ 2011 89 (10) 766-774E OBJECTIVE: To update the estimated global incidence of Japanese encephalitis (JE) using recent data for the purpose of guiding prevention and control efforts. METHODS: Thirty-two areas endemic for JE in 24 Asian and Western Pacific countries were sorted into 10 incidence groups on the basis of published data and expert opinion. Population-based surveillance studies using laboratory-confirmed cases were sought for each incidence group by a computerized search of the scientific literature. When no eligible studies existed for a particular incidence group, incidence data were extrapolated from related groups. FINDINGS: A total of 12 eligible studies representing 7 of 10 incidence groups in 24 JE-endemic countries were identified. Approximately 67,900 JE cases typically occur annually (overall incidence: 1.8 per 100,000), of which only about 10% are reported to the World Health Organization. Approximately 33,900 (50%) of these cases occur in China (excluding Taiwan) and approximately 51,000 (75%) occur in children aged 0-14 years (incidence: 5.4 per 100,000). Approximately 55,000 (81%) cases occur in areas with well established or developing JE vaccination programmes, while approximately 12,900 (19%) occur in areas with minimal or no JE vaccination programmes. CONCLUSION: Recent data allowed us to refine the estimate of the global incidence of JE, which remains substantial despite improvements in vaccination coverage. More and better incidence studies in selected countries, particularly China and India, are needed to further refine these estimates. |
Report of the 7th meeting on Evaluation of Pandemic Influenza Vaccines in Clinical Trials, World Health Organization, Geneva, 17-18 February 2011
Girard MP , Katz JM , Pervikov Y , Hombach J , Tam JS . Vaccine 2011 29 (44) 7579-86 On February 17-18, 2011, the World Health Organization convened the 7th meeting on "The Evaluation of Pandemic Influenza Vaccines in Clinical Trials" to review the progress made on pandemic A (H1N1) 2009 vaccines and the evaluation of their effectiveness in the field, especially in children less than 3 years of age and in pregnant women. Other topics to be addressed included a comparison of egg- and cell culture-based influenza vaccines, technical issues related to vaccine strain development and vaccine potency, and the status of development of prototype influenza vaccines using new technologies. Pandemic A (H1N1) vaccines were safe in young children, pregnant women and immunocompromized individuals. Overall effectiveness of inactivated A (H1N1) vaccines for all ages was found to vary between 72% and 100% in different countries and with different vaccine preparations. Effectiveness of pandemic A (H1N1) 2009 live attenuated vaccine was estimated to be approximately 80% in pediatric populations in the USA. A single dose of inactivated vaccine adjuvanted with AS03, MF59 or AF03 induced protective immunity in young children and pregnant women. However, unadjuvanted vaccines as well as low dose adjuvanted vaccines (1.9 mcg HA) required two doses to elicit protective antibody levels in these populations. Clinical trials of influenza vaccines developed using new technologies showed they were well tolerated and induced antibody and/or T cell immune responses to viral proteins. Further studies are warranted to validate novel immunological criteria for evaluation and licensing of such new influenza vaccine concepts. On the regulatory side, work should be undertaken to harmonize the results of serological tests used to evaluate the immunogenicity of traditional influenza vaccines. |
Next generation dengue vaccines: a review of candidates in preclinical development.
Schmitz J , Roehrig J , Barrett A , Hombach J . Vaccine 2011 29 (42) 7276-84 Dengue represents a major public health problem of growing global importance. In the absence of specific dengue therapeutics, strategies for disease control have increasingly focused on the development of dengue vaccines. While a licensed dengue vaccine is not yet available, several vaccine candidates are currently being evaluated in clinical trials and are described in detail in accompanying articles. In addition, there are a large variety of candidates in preclinical development, which are based on diverse technologies, ensuring a continued influx of innovation into the development pipeline. Potentially, some of the current preclinical candidates may become next generation dengue vaccines with superior product profiles. This review provides an overview of the various technological approaches to dengue vaccine development and specifically focuses on candidates in preclinical development. |
Models of the impact of dengue vaccines: a review of current research and potential approaches
Johansson MA , Hombach J , Cummings DA . Vaccine 2011 29 (35) 5860-8 Vaccination reduces transmission of pathogens directly, by preventing individual infections, and indirectly, by reducing the probability of contact between infected individuals and susceptible ones. The potential combined impact of future dengue vaccines can be estimated using mathematical models of transmission. However, there is considerable uncertainty in the structure of models that accurately represent dengue transmission dynamics. Here, we review models that could be used to assess the impact of future dengue immunization programmes. We also review approaches that have been used to validate and parameterize models. A key parameter of all approaches is the basic reproduction number, R(0), which can be used to determine the critical vaccination fraction to eliminate transmission. We review several methods that have been used to estimate this quantity. Finally, we discuss the characteristics of dengue vaccines that must be estimated to accurately assess their potential impact on dengue virus transmission. |
Health economics of dengue: a systematic literature review and expert panel's assessment
Beatty ME , Beutels P , Meltzer MI , Shepard DS , Hombach J , Hutubessy R , Dessis D , Coudeville L , Dervaux B , Wichmann O , Margolis HS , Kuritsky JN . Am J Trop Med Hyg 2011 84 (3) 473-488 Dengue vaccines are currently in development and policymakers need appropriate economic studies to determine their potential financial and public health impact. We searched five databases (PubMed, EMBASE, LILAC, EconLit, and WHOLIS) to identify health economics studies of dengue. Forty-three manuscripts were identified that provided primary data: 32 report economic burden of dengue and nine are comparative economic analyses assessing various interventions. The remaining two were a willingness-to-pay study and a policymaker survey. An expert panel reviewed the existing dengue economic literature and recommended future research to fill information gaps. Although dengue is an important vector-borne disease, the economic literature is relatively sparse and results have often been conflicting because of use of inconsistent assumptions. Health economic research specific to dengue is urgently needed to ensure informed decision making on the various options for controlling and preventing this disease. |
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