Background on the WHO’s Strategic Advisory Group of Experts (SAGE)
The World Health Organization’s (WHO) Strategic Advisory Group of Experts (SAGE) is a panel of international experts that provides advice on vaccine-preventable diseases. The group recently met from September 22 to 25, 2023, to discuss global immunization contexts and propose recommendations for improving vaccine coverage and population protection.
Key Recommendations
The SAGE recommended vaccinating against avian influenza A(H5), or bird flu, for high-risk population groups during interpandemic periods and emergencies. These high-risk groups include:
- First responders in zoonotic influenza outbreaks
- Healthcare workers evaluating and managing suspected or confirmed human cases, including potential vaccinators
- Individuals in continuous contact with animals or their environments in areas where animal or human infections have been reported
Global Vaccination Coverage and Challenges
The SAGE acknowledged that global vaccination coverage has largely recovered pre-pandemic levels, but significant disparities remain between countries. They highlighted the increasing complexity of immunization programs due to geopolitical instability, limited global funding, reduced national health budgets, and changes in health system architectures.
The group emphasized the importance of supporting countries in strengthening their immunization systems through the Agenda 2030 for Immunization (AI2030). They called for reviewing global and regional structures of the AI2030 agenda to reinforce a coordinated approach towards common priorities at all levels.
Malaria and Polio
After reviewing available evidence, the SAGE reaffirmed its recommendation for a four-dose regimen to ensure optimal protection against malaria in moderate to high transmission areas, rather than the three-dose regimen. They also suggested aligning the fourth dose with other health interventions during a child’s second year of life.
The SAGE expressed deep concern about the ongoing wild poliovirus transmission in Pakistan and Afghanistan, persistent circulating vaccinator-derived poliovirus type 2 (cVDPV2) transmission in many African countries, and continued detection of cVDPV2 in European sewage samples.
- The SAGE stressed the need to intensify efforts to improve immunization coverage and reach unvaccinated children.
- They supported the safe discontinuation of bivalent oral polio vaccine (bOPV) in mass immunization and urged resource mobilization for this safe discontinuation.
- The SAGE recommended fractional doses, including intradermal administration, of Sabin-based inactivated polio vaccines (IPV) similar to Salk-based fractional dose IPV use. They also supported expanding the use of the new oral polio vaccine type 2 (nOPV2) as part of the response to reduce cVDPV2 transmission in specific geographic areas with persistent cVDPV2 transmission.
Covid-19 and Tuberculosis
During discussions on Covid-19, SAGE experts noted a decrease in global cases and deaths between 2024 and 2025. However, they warned that annual vaccination rates remain low, primarily in high-income countries within WHO regions of Europe, the Americas, and the Western Pacific.
Regarding variant-specific Covid vaccines, SAGE pointed out moderate relative efficacy in preventing cases and hospitalizations, though protection wanes after six months. They recommended reviewing the current roadmap and evidence on variant vaccine effectiveness, particularly against the Ómicron variant, and approved developing a position statement on evidence-based vaccine development.
Tuberculosis Vaccine Development
Regarding tuberculosis, SAGE noted that as of May 2025, there were 16 candidate vaccines in clinical development, with five in phase 3 trials evaluating disease prevention. The M72/ASO1E candidate might receive marketing authorization in 2028, contingent on trial results.
Lastly, SAGE supported the development of a framework to identify, analyze, and prioritize new combined vaccines. They highlighted the potential of these vaccines to assist countries in distributing existing vaccines and introducing new ones by reducing the number of required injections.
Key Questions and Answers
- Who is SAGE? The Strategic Advisory Group of Experts is a panel of international experts advising the WHO on vaccine-preventable diseases.
- What is the main recommendation? Vaccinate high-risk groups against avian influenza during interpandemic periods and emergencies.
- What challenges does global vaccination face? Geopolitical instability, limited funding, reduced national health budgets, and changes in health system architectures.
- What is the SAGE’s stance on malaria and polio vaccines? Recommend a four-dose regimen for malaria and support the safe discontinuation of bivalent oral polio vaccine (bOPV) in mass immunization.
- What concerns does SAGE have about Covid-19 and polio? Low annual vaccination rates for Covid-19, particularly in high-income countries, and ongoing poliovirus transmission in Pakistan and Afghanistan.
- What is the status of tuberculosis vaccine development? As of May 2025, there are 16 candidate vaccines in clinical development, with five in phase 3 trials. The M72/ASO1E candidate might receive marketing authorization in 2028.
