Q&A Feature on how the World Health Organization turns vaccine evidence into immunization guidance
SPECIAL FEATURE WITH THE IMMUNIZATION AND VACCINE POLICY TEAM - IMMUNIZATION, VACCINES AND BIOLOGICALS DEPARTMENT, WORLD HEALTH ORGANIZATION.
1. What are immunization policies, and why do countries need them to make vaccination decisions?
The World Health Organization (WHO) immunization strategies and policies provide countries with independent, evidence-based guidance on how vaccines can be used safely, effectively and equitably. They synthesize an increasingly complex body of scientific evidence to inform global vaccine policy recommendations aimed at maximizing public health impact. These global recommendations provide a common evidence-based foundation for immunization policy, while recognizing the need for adaptation to regional and national contexts, including local epidemiology, health system capacities, public health priorities and available resources. WHO recommendations thus inform and support, rather than replace, national decision-making on vaccine introduction, target populations, immunization schedules and delivery strategies.
2. How does the WHO use the advice of the Strategic Advisory Group of Experts on Immunization to develop immunization recommendations?
The Strategic Advisory Group of Experts on Immunization (SAGE) brings together independent immunization experts who review the available evidence and consider not only vaccine safety and conferred protection, but also factors such as disease burden, public health impact, equity, cost-effectiveness and programmatic feasibility. SAGE provides recommendations to WHO, which, once endorsed by the WHO Director-General, become WHO recommendations and may subsequently be reflected in WHO vaccine position papers and other guidance documents.
3. How does SAGE assess new evidence when important questions remain unanswered or the evidence is evolving rapidly?
Uncertainty is an inherent part of evidence-based policymaking, particularly when scientific evidence is evolving rapidly. SAGE systematically evaluates the available evidence and its certainty, using established methodologies such as GRADE and Evidence-to-Decision frameworks. In formulating recommendations, SAGE weighs the anticipated benefits and risks alongside considerations of feasibility, equity, acceptability and public health impact. Where important evidence gaps or uncertainties remain, these are explicitly acknowledged and transparently communicated. Such gaps also help define research priorities and inform the need for future policy reviews and updates as new evidence emerges.
4. How can countries adapt global immunization recommendations to their own disease patterns, health systems and resources, and what role do national immunization technical advisory groups play?
WHO provides global evidence-based immunization recommendations, which may be further contextualized at the regional level through Regional Immunization Technical Advisory Groups (RITAGs). Countries retain responsibility for national immunization policy decisions, supported by National Immunization Technical Advisory Groups (NITAGs). NITAGs play a critical role in assessing global and regional recommendations in light of local disease epidemiology, health system capacities, immunization programme priorities, equity considerations and available resources. At its October 2026 meeting, SAGE specifically emphasized the importance of strengthening and adequately supporting NITAGs to enable independent, evidence-informed national policy recommendations. Ultimately, translating global recommendations into public health impact depends on countries adapting policies to their specific contexts, informed by NITAG assessments, and ensuring their effective implementation through strong immunization programmes.
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Further information: Strategic Advisory Group of Experts on Immunization