Sabin Vaccine Institute (Sabin), located in Washington, D.C., is a nonprofit organization promoting global vaccine development, availability, and use. Through its work, Sabin hopes to reduce human suffering by preventing the spread of vaccine-preventable, communicable disease in humans through herd immunity and mitigating the poverty caused by these diseases.
Background/Objectives: Transitions to new vaccines or antigen schedules represent complex system changes requiring coordinated governance, reliable data systems, domestic financing, and multisectoral collaboration. In 2025, African countries were moving toward a switch from separate pentavalent and inactivated poliovirus vaccines to the combined hexavalent vaccine. This project report describes the Hexavalent Vaccine Switch Early Adopters Workshop in Dakar, Senegal, which included ten African countries, and its implications for future vaccine introductions. Methods: We conducted a practice analysis drawing on structured documentation of plenary presentations, country case studies, interactive problem-solving sessions, and national roadmap exercises. A thematic framework aligned to ten process points for the hexa switch guided synthesis. Results: Countries reported shared system vulnerabilities, including coexistence risks of legacy and new vaccine stocks, inconsistent data completeness, under-resourced vaccine safety surveillance, and financing uncertainties. Early adopter countries demonstrated operational feasibility, logistical efficiencies, and opportunities for reducing injection burden. Outputs included a Health System Adaptation Checklist, a Switch Risk Mitigation Catalog, and 12-month national roadmaps. Conclusions: Regional peer-learning mechanisms can accelerate decision-making, improve operational quality, and strengthen accountability for vaccine introductions. Structured cross-country collaborations can transform a product switch into a scalable system-strengthening opportunity.
Influenza vaccination programs are critical in reducing the morbidity and mortality from seasonal influenza and bolstering pandemic preparedness. However, there is a notable lack of information about the factors contributing to resilient and response-ready influenza vaccination programs in middle-income countries (MICs). This study set out to identify determinants of resilient and response-ready seasonal influenza vaccination programs in MICs. This study used a collective case study design to analyze structural and programmatic elements of resiliency and response-readiness within MIC influenza vaccination programs. A multi-step process was used to select suitable countries for the case study analysis, including an initial literature landscaping of MICs, stakeholder mapping, and an online scoping survey. A conceptual framework was developed to guide analysis across six determinants of resilient and response-ready programs: political, economic, structural, communication education, socio-behavioral, and COVID-19 response. Data for the selected case studies were gathered via a narrative literature review (initial search conducted January−September 2022) and stakeholder consultations with 27 stakeholders (held between June and September 2022). Findings from the literature review and stakeholder consultations were analyzed using the framework to identify key themes related to influenza vaccination program resiliency and response-readiness. Five countries – Albania, Bolivia, Brazil, South Africa, and Thailand – met the study selection criteria and were selected as geographically diverse case studies. Five key themes emerged as consistent indicators of resilient and response-ready influenza vaccination programs: 1) building research capacity and a clear pathway from evidence to policy creates resilient and responsive influenza programs; 2) diversified procurement mechanisms help ensure a reliable supply of influenza vaccines; 3) healthcare workers are essential partners for implementing resilient and response-ready influenza vaccination programs; 4) demand generation is key to driving and maintaining influenza vaccine uptake; and 5) building and maintaining seasonal influenza vaccine infrastructure contributes to pandemic preparedness. The findings offer valuable insights and actionable guidance to improve influenza vaccination program resiliency and response-readiness in MICs and more broadly. Strengthening areas highlighted in this evaluation can help countries improve influenza vaccination coverage while building greater program resilience and readiness to respond to future public health threats, including influenza pandemics.
Background:Enteric fever, caused by Salmonella Typhi or Paratyphi, is a major public health issue in low- and middle-income countries. Accurate burden estimation is hampered by limited microbiological facilities and low sensitivity of blood-culture tests. Serosurveillance offers a scalable alternative to address these challenges. This study estimated the seroincidence of enteric fever in Bangladesh using cross-sectional rapid serosurveys. Methods:School-based surveys (January-June 2022) were conducted in Chattogram, Dinajpur, Sylhet, Satkhira, and Faridpur, and community-based surveys (July 2019-November 2021) were conducted in Dhaka and Mirzapur. Blood samples (dried blood spots or venous blood) were collected and tested for anti-hemolysin E IgG responses using a kinetic enzyme-linked immunosorbent assay. Seroincidence was estimated using a maximum likelihood approach based on peak antibody titers and decay rates, modeled from blood-culture confirmed enteric fever cases in Bangladesh. Findings:A total of 2969 participants aged 0-22 years were enrolled, with 75.5% aged 5-15 years. Seroincidence rates (per 100 person-years) were highest in Dhaka (33.1; 95% confidence interval [CI], 29.0-37.9), followed by Mirzapur (19.5; 95% CI, 17.4-21.7) and Chattogram (17.1; 95% CI, 15.0-19.4), and the lowest in Faridpur (11.1; 95% CI, 9.6-12.7). The under 5 age group exhibited higher rates in Dhaka (40.3; 95% CI, 32.1-50.7) and Mirzapur (26.1; 95% CI, 21.0-32.4) compared to older age groups. Seroincidence was higher in areas with higher population density. Conclusions:This study highlights a substantial burden of enteric fever infections across Bangladesh. These provide important evidence to guide post-introduction monitoring and optimization of the typhoid conjugate vaccine program in the national immunization schedule.
Since endorsement of the Global Vaccine Action Plan, and continued emphasis under Immunization Agenda 2030, the number of functional National Immunization Technical Advisory Groups (NITAGs) has expanded rapidly, creating increased demand for training in evidence-informed decision making. To support timely national policy decisions relating to immunization, innovative and flexible training approaches are needed. This paper describes and evaluates a novel, webinar-based Evidence-to-Recommendation (EtR) training designed to support NITAGs in developing evidence-based recommendations for transitioning from pentavalent plus inactivated polio vaccine to combined hexavalent vaccines. Between January and June 2025, a five-part EtR webinar series focused on the hexavalent vaccine transition was delivered to countries, primarily within the WHO African Region, who qualify to receive financial and technical support from Gavi, the Vaccine Alliance, to help introduce new vaccines and strengthen their immunization systems. The series emphasized identification of evidence across EtR domains, and a cohort-based model to facilitate regional peer learning. Effectiveness of the webinar series was assessed through electronic post-webinar surveys and virtual key informant interviews. NITAGs from 32 countries participated in one or more webinars, including nine in three or more. Across participating countries, participants consistently rated the webinars as useful, particularly valuing country experiences and practical guidance on EtR domains. Qualitative feedback highlighted peer learning as the most valuable component of the webinar series, alongside practice guidance on EtR domains such as feasibility and resource considerations, and NITAGs showed strong interest in continued technical support, practical, peer-to-peer learning or "twinning", and operational guidance for hexavalent vaccine introduction.
Twenty years after the introduction of rotavirus vaccines, the 15th International Rotavirus Symposium convened researchers, clinicians, immunization program managers, and policymakers to review advances in rotavirus epidemiology, immunology, vaccine development, and implementation. Rotavirus vaccination has contributed to sustained reductions in severe rotavirus hospitalizations and child mortality, yet population-level benefits remain heterogeneous and are constrained by gaps in coverage, supply-related program disruptions, and context-specific vaccine performance. Presenters highlighted evidence from multi-pathogen surveillance confirming that rotavirus remains a leading cause of pediatric diarrhea requiring hospitalization despite widespread vaccine introduction. Accumulating evidence implicates maternally derived antibodies, environmental enteric dysfunction, and early-life microbiome development as contributors to reduced oral vaccine performance in low- and middle-income communities, while recent studies of next-generation vaccine candidates underscore the need for improved correlates of protection and clinically meaningful efficacy endpoints. Collectively, the symposium emphasized that further reductions in rotavirus morbidity and mortality will require strengthening delivery of existing vaccines—including improving coverage, minimizing supply interruptions, and reaching zero-dose and under-immunized children—while sustaining surveillance and investing in integrated enteric disease prevention and next-generation vaccines to optimize protection in high-burden settings.
