Title : Safeguarding polio eradication under fiscal constraint: A scoping review of transmission, immunization coverage, response timeliness, and contextual vulnerability
Abstract:
Introduction: Donor reprioritization and fiscal uncertainty threaten the global polio endgame. No scoping review has mapped how fiscal constraint intersects with polio transmission trends, routine immunization coverage, outbreak response timeliness, and contextual vulnerability using publicly auditable programmatic sources.
Methods: Following PRISMA-ScR and JBI methodology, we searched MEDLINE, WHO IRIS, and Global Index Medicus (January 2015 to December 2025) alongside WHO POLIS and the WUENIC 2024 revision. Annual polio transmission and immunization coverage data were charted for 243 countries. A tiered risk quadrant was constructed from 2024 immunization coverage and 2024–2025 transmission data. Outbreak response indicators were extracted as structured narrative data from official sources for 16 settings. Risk context flags included conflict/fragility (World Bank FCS 2026), land-border adjacency to polio-affected countries, and DTP1–DTP3 dropout rate as a zero-dose proxy.
Results: Wild poliovirus type 1 (WPV1) cases rebounded to 99 in 2024 from a low of 6 in 2021. Circulating vaccine-derived poliovirus (cVDPV, any type) cases peaked at 1,117 in 2020 and declined to 463 in 2024 following novel Oral Polio Vaccine type 2 (nOPV2) rollout. Global median Pol3 declined from 93% in 2019 to 89% in 2021 and recovered partially to 90% by 2024; 51 countries remained below 80%. Of 194 classifiable countries, 25 (12.9%) were classified as High primary risk tier, all in WHO African Region (AFRO) or WHO Eastern Mediterranean Region (EMRO). Conflict/fragile countries (n=38) accounted for 81% of global cases in 2024–2025. 13 countries simultaneously experienced active transmission, conflict/fragility, and border adjacency, accounting for 55% of global cases. The only official document explicitly linking response scheduling to financing and supply constraints covered 6 High-tier Sahel countries.
Conclusions: Fiscal constraint risks amplifying transmission precisely in the settings least able to absorb it. The 13 triple-risk countries represent the minimum protected perimeter under any resource triage framework, and risk-informed prioritization guided by reproducible, publicly auditable evidence is essential to safeguard the polio endgame.
