Polio Remains a Global Health Emergency as Vaccination Gaps Persist

Afghanistan and Pakistan remain the only two countries where WPV1 is endemic, even as recent figures show a substantial decline.

The global fight against polio has moved closer to its final goal, with fewer wild and vaccine-derived poliovirus cases being recorded; still, the disease continues to find children who have been missed by vaccination programmes, particularly in communities affected by conflict, insecurity and displacement. The latest assessment from the Emergency Committee under the International Health Regulations found that wild poliovirus type 1, known as WPV1, remains endemic in Afghanistan and Pakistan, while outbreaks of circulating vaccine-derived polioviruses continue across several countries. The committee concluded that the international spread of poliovirus still represents a Public Health Emergency of International Concern, keeping global attention firmly on vaccination, surveillance and cross-border cooperation.

Afghanistan and Pakistan remain at the centre of wild polio transmission

Afghanistan and Pakistan remain the only two countries where WPV1 is endemic, even as recent figures show a substantial decline. Four WPV1 cases had been reported in 2026 at the time of the assessment, including three in Afghanistan and one in Pakistan, compared with 52 cases during 2025. Environmental surveillance had identified 74 positive samples in 2026, with 17 from Afghanistan and 57 from Pakistan, compared with 747 positive samples recorded during 2025. Transmission has survived the recent low-transmission season, with southern Afghanistan, South Khyber Pakhtunkhwa and Karachi remaining particularly important reservoirs where the virus continues to circulate.

Vaccination teams face very different challenges across these areas. Afghanistan has relied on site-to-site vaccination since house-to-house campaigns stopped in October 2024 because of security concerns, making it harder to reach every young child, while the limited number of women working in vaccination teams creates another obstacle in some communities. Pakistan has reported strong national and provincial vaccination coverage, yet district-level performance remains uneven, particularly in areas affected by insecurity. Around 250,000 children in South Khyber Pakhtunkhwa were reportedly unreached, showing how a relatively small number of difficult-to-access communities can keep transmission alive even during periods of wider progress.

Vaccine-derived outbreaks continue across several countries

Circulating vaccine-derived poliovirus remains another major part of the global polio challenge. As of 30 April 2026, 32 cVDPV cases and 27 positive environmental detections had been reported across 12 countries, compared with 238 cases and 247 environmental detections across 30 countries during 2025. Most cases reported in 2026 were cVDPV2, with Nigeria accounting for 14 cases, or half of the global cVDPV2 caseload recorded at that point. Nigeria was also dealing with simultaneous cVDPV2 and cVDPV3 outbreaks.

There is encouraging evidence around novel oral polio vaccine type 2, or nOPV2, which has shown greater genetic stability and a much lower risk of reverting toward neurovirulence than the older Sabin OPV2. More than two billion doses have been administered since its introduction in 2021, and more than 80% of cVDPV2-affected countries have stopped outbreaks with three or fewer supplementary immunization activities using nOPV2. The remaining outbreaks are strongly connected with inaccessible communities, insecurity, displacement and large numbers of zero-dose or under-immunized children.

Millions of children remain difficult to reach

The hardest parts of the eradication campaign increasingly overlap with humanitarian crises. Northern Yemen has more than 4.5 million children under five who remain susceptible while insecurity and access restrictions have prevented a proper oral polio vaccine response to the continuing cVDPV2 outbreak. Nigeria continues to struggle with reaching every child in high-risk northern states, while more than 450,000 children have been missed during campaigns in southern and central Somalia.

Movement between countries creates another route for poliovirus to reach populations with immunity gaps. Genetic analysis documented at least 13 international cVDPV importation events between January 2025 and January 2026, including transmission links stretching across Africa, Europe and the Pacific. WPV1 was also detected in wastewater in Germany in October 2025, demonstrating why countries without endemic transmission still need strong surveillance systems capable of quickly identifying imported virus.

Funding and surveillance could decide the final push

The committee warned that a financial shortfall estimated at nearly 30% now threatens essential parts of the eradication programme, including sensitive surveillance systems needed to detect poliovirus before transmission spreads further. Higher transportation and fuel costs, pressure on international health funding and difficult geopolitical conditions are making vaccination and surveillance work more expensive at precisely the stage when programmes need to reach the hardest-to-access children.

The message from the latest assessment is that declining case numbers represent important progress, but eradication requires more than keeping infections low. Countries need strong routine immunization, rapid outbreak responses, reliable laboratory networks, vaccination for migrants and other mobile populations, and coordinated action across borders. Until the remaining transmission chains are broken, a child missed by vaccination in one difficult-to-reach community can become part of a much wider international health challenge.