Key result
WPV1 cases surge in Afghanistan and Pakistan while global cVDPV cases drop ~12%.
Why the study?
Outbreaks of circulating vaccine-derived polioviruses continue to challenge polio eradication goals, making understanding the epidemiologic, surveillance, and operational factors associated with persistent transmission critical as the eradication target is extended to 2029.
Observational
While WPV1 outbreaks in Africa have ended, a substantial resurgence of WPV1 in Afghanistan and Pakistan and the geographic expansion of cVDPVs pose significant challenges to global polio eradication.
Resurgence of WPV1 and expanding cVDPV detections challenge eradication timelines; leaves open optimal strategies for missed children and surveillance.
Background Since the establishment of the Global Polio Eradication Initiative (GPEI) in 1988, wild poliovirus type 1 (WPV1) remains endemic in only Afghanistan and Pakistan. However, outbreaks of paralytic polio caused by circulating vaccine-derived polioviruses (cVDPVs) emerge in areas with low vaccination coverage and continue to challenge polio eradication goals. As the Global Polio Eradication Initiative extends its eradication target to 2029, understanding the epidemiologic, surveillance, and operational factors associated with persistent transmission is critical for informing policy decisions and targeting limited resources. This report describes global polio immunization efforts, surveillance activities, and epidemiology during January 2023–December 2024. Methods Surveillance and virologic data were obtained from the World Health Organization’s (WHO) global Polio Information System (POLIS), and immunization coverage estimates were sourced from WHO’s Immunization Dashboard, which incorporates administrative and survey-based data from WHO and UNICEF. A cVDPV outbreak was defined using standardized acute flaccid paralysis (AFP) and environmental surveillance criteria; analyses were conducted in R (version 4.4.1). Results Afghanistan and Pakistan reported 99 WPV1 cases in 10 provinces in 2024, compared with 12 cases in 3 provinces in 2023. cVDPV cases decreased 12% from 529 in 2023 to 464 in 2024. However, cVDPV detections from AFP and environmental surveillance expanded geographically, with detections in 40 countries in Africa, Southeast Asia, the Middle East and Europe in 2024, including 14 countries with no detections in 2023. The resurgence of WPV1 in polio-free regions in Afghanistan and Pakistan and the spread of cVDPVs challenge global polio eradication. Conclusions Achieving global polio eradication will require reaching persistently missed children in remote and insecure areas, strengthening vaccination and surveillance systems, and reinforcing accountability to improve campaign quality. The geographic expansion of cVDPV type 2 (cVDPV2) underscores the need for rapid detection, expanded nOPV2 use in areas with prolonged transmission, and sustained partner engagement and strategic resource allocation amid declining global health funding.
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Whitmire et al. (2026) conducted an observational in Poliomyelitis. Global Polio Eradication Initiative efforts (vaccination and surveillance) vs. 2023 baseline data was evaluated on Number of wild poliovirus type 1 (WPV1) and circulating vaccine-derived poliovirus (cVDPV) cases. Wild poliovirus type 1 cases increased from 12 in 2023 to 99 in 2024 in Afghanistan and Pakistan, while circulating vaccine-derived poliovirus cases decreased by 12% globally despite geographic expansion.
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