Supporting the Transition from Pentavalent to Hexavalent Vaccines
The introduction of the hexavalent (Hexa) vaccine — which combines protection against six diseases into a single shot — presents a unique opportunity to streamline infant immunization schedules in low- and middle-income countries. Transitioning from separate administrations of pentavalent (a combination of diphtheria, tetanus, pertussis, hepatitis B, and Haemophilus influenzae type B antigens) and inactivated polio (IPV) vaccines to the single Hexa vaccine can improve program efficiency, reduce missed opportunities, and potentially increase coverage of all six antigens.
To support this critical transition, Gavi, the Vaccine Alliance has partnered with the Sabin-led Hexavalent Vaccine (Switch) Assessment Consortium (HeVAC) to identify key enablers and barriers for a successful transition and to evaluate its impact. This work directly supports Gavi’s commitment to help countries increase coverage and equity by making immunization systems more efficient, resilient, and accessible — especially for zero-dose and under-immunized children.
Project Overview
Sabin Vaccine Institute is leading the HeVAC to conduct process evaluations in Mauritania and Madagascar, and knowledge-sharing activities amongst Gavi-eligible countries in the African region to inform decision-making, support implementation, and assess outcomes from the national-level Hexa vaccine transition.
The project features an innovative engagement and learning mechanism, which brings together members of national immunization technical advisory groups (NITAG) and Expanded Programmes on Immunization (EPI) for experience-sharing, collaboration, and continued capacity-building using the Evidence to Recommendations (EtR) methodology.
Hexavalent Vaccine (Switch) Assessment Consortium Partners:
- Agence de Médecine Préventive Afrique (Mauritania)
- eBASE Africa
- Makerere University School of Public Health
- Société Malgache de Pédiatrie (Madagascar)
- Task Force for Global Health
- WHO Regional Office for Africa (WHO AFRO)
Location
Hexa planning and implementation research activities are underway in Mauritania, which initiated Hexa vaccination for children under one year of age on July 1, 2025, and Madagascar, which is set to transition in January 2026.
The Consortium’s NITAG and EPI peer engagement and learning collaborative has participation from over 30 countries — with a particular focus on representation from the WHO AFRO region — which have expressed interest in or are preparing for or implementing a Hexa vaccine transition.
Aims and Objectives
The project is designed to:
- Support the design and implementation of the Hexa transition in Gavi-supported countries
- Identify challenges and facilitators during the transition from pentavalent + IPV to Hexa
- Measure the transition’s impact on vaccine coverage, especially for IPV, and other linked immunization services
- Strengthen the evidence-based decision-making capacity of NITAGs through tailored technical support and cross-country learning and engagement
- Collect real-world evidence on Hexa program costs to inform Gavi’s financial support and co-financing policies
Our Approach
As Consortium leader, Sabin brings deep experience in convening and managing multi-country research consortia and leading implementation research and peer learning and engagement platforms across diverse settings.
The HeVAC leverages expertise in process evaluation design, vaccine policy decision-making, health economics, data governance, capacity-building for immunization advisory bodies, and rapid generation of actionable evidence.
Study activities are conducted in close collaboration with Consortium partners who bring specialized expertise in health systems research, data governance, policy advisory support, and regional coordination. We will leverage their deep knowledge of local health systems, strong relationships with national immunization stakeholders, and proven track records supporting vaccine introductions, transition assessments, and impact evaluations. This approach fosters bi-directional learning, supports country-led adaptation, and ensures contextualized implementation across participating countries.
Our implementation-forward monitoring, evaluation, and learning approach will support real-time feedback and continuous improvement of Hexa transition activities, while capturing lessons that can inform broader vaccine policy and planning. Through the NITAG/EPI learning and engagement mechanism, the project also promotes peer learning, strengthens national advisory bodies, and advances country-driven, evidence-informed decision-making.
Five-Phase Methodology
To generate timely, relevant, and actionable evidence, the HeVAC project follows a five-phase methodology. Each phase is designed to align with country priorities, ensure stakeholder engagement, and support real-time learning and adaptation throughout the Hexa transition process.
Phase 1: Stakeholder consultations and literature reviews: The project began with in-depth consultations with stakeholders — including Ministries of Health, NITAGs, and EPI teams — and a rapid review of global and country-specific evidence. This phase identified local priorities, informed protocol development, and ensured relevance to country needs.
Phase 2: Protocol development and IRB approvals: Insights from Phase 1 guided the development of country-specific protocols that outline the study’s aims, methods, and ethical considerations. These protocols were submitted to local Institutional Review Boards to ensure alignment with national research standards and timelines.
Phase 3: Data collection and monitoring: The HeVAC is using mixed methods — including key informant interviews, focus group discussions, and administrative data analysis — to gather timely, actionable evidence on the Hexa transition process and outcomes. Data collection tools were tailored to each country’s context and co-designed with local partners.
Phase 4: Rapid data analysis and synthesis: Rapid review and analysis cycles are identifying challenges, enabling factors, and lessons learned. Findings will be synthesized to inform in-country decision-making and shared with national NITAGs/EPI to support evidence-based recommendations.
Phase 5: Dissemination of findings and lessons learned: The project will facilitate cross-country learning through the learning and engagement mechanism and peer exchanges, including an Early Adopters’ Workshop. Final findings will be disseminated at national, regional, and global levels to inform broader adoption of the Hexa vaccine and improve future transition strategies.
Through the HeVAC, Sabin will host a three-day in-person “Early Adopters” workshop in November 2025 in Dakar, Senegal to convene representatives from early adopter countries (i.e., Mauritania, Senegal, Burundi, Madagascar), countries that have applied to make the transition in the coming year (i.e., Chad, Liberia), and potential adopters (i.e., Rwanda, Togo, Uganda, Zimbabwe). The goal of this regional peer engagement and learning event is for early-adopting countries to share and synthesize lessons learned around decision-making, preparation and implementation; and optimize existing implementation process-point support tools to strengthen service delivery among implementing countries and best prepare future adopting countries.
Local Impact
Locally, the project seeks to:
- Improve the efficiency and coverage of immunization programs in Mauritania and Madagascar, with a focus on polio (IPV), diphtheria-tetanus-pertussis (DTP)-containing vaccines, and other antigens included in the Hexa formulation
- Strengthen the capacity of Ministries of Health and NITAGs in evidence-based decision-making, program planning, and effective implementation of vaccine transitions
- Provide real-time insights to inform Hexa immunization implementation adjustments
Global impact
Globally, the project will:
- Generate scalable models for Hexa transition implementation
- Offer lessons to strengthen vaccine policy and program planning
- Inform Gavi’s co-financing policy for Hexa immunization
- Feed into Gavi’s broader learning agenda on immunization program innovations
Preliminary findings will be shared in early 2026.
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