Polio continues to affect children in a small number of countries despite global efforts to eradicate the disease, highlighting persistent challenges in vaccination coverage and public health outreach. While most nations have eliminated polio through routine immunization programs, recent cases underscore the persistent risks in areas with low vaccination rates and ongoing conflict.

Polio is a viral disease that primarily spreads through contaminated water, food, or hands, particularly in regions lacking adequate sanitation. The virus often causes no symptoms but can lead to paralysis in about one in 200 cases when it attacks the nervous system. There is no cure for polio, but immunization provides effective lifelong protection.

Global eradication efforts that began in 1988 have drastically reduced polio cases from approximately 350,000 annually across 125 countries to just a few dozen reported cases in a handful of nations. Currently, only wild poliovirus type 1 remains in circulation, restricted to Afghanistan and Pakistan. In 2025, these two countries reported 52 cases of paralysis caused by the virus. Prolonged armed conflict and security risks have hindered vaccination campaigns in these regions; for example, house-to-house immunization ceased in Afghanistan in late 2024, requiring parents to bring children to centralized locations such as mosques, where some remain missed.

In addition to wild polio, vaccine-derived poliovirus outbreaks have emerged in areas with insufficient vaccine coverage. Oral polio vaccine (OPV) contains a weakened form of the virus that, while unable to cause illness in vaccinated children, can be excreted and transmitted in communities where vaccination rates fall below 80 percent. As the virus circulates, it can mutate back into a form capable of causing paralysis. These outbreaks expose challenges in reaching marginalized populations, including those in remote or conflict-affected regions. Studies in Pakistan suggest that integrating other health services with polio vaccination may improve uptake among unvaccinated groups.

Polio virus traces have recently been detected outside endemic countries through wastewater surveillance. In 2025, wild poliovirus was identified in sewage samples in Hamburg, Germany, genetically linked to strains from Afghanistan. Similar findings of vaccine-derived poliovirus occurred in other European countries, although no paralytic cases were reported due to high immunization coverage. These incidents illustrate that the virus can spread globally through asymptomatic carriers but typically causes disease only where vaccination is inadequate.

Misinformation has also played a role in undermining vaccination efforts. In 2003, false claims about vaccine safety in northern Nigeria led to a suspension of immunization campaigns and a subsequent outbreak that exported the virus to multiple countries. Experts warn that misinformation spreads rapidly online, potentially reversing progress even in countries that eliminated polio decades ago. In the United States, incomplete vaccination coverage remains a concern; for instance, about 12.5 percent of kindergarteners in Colorado have not completed the polio vaccine series, and vaccine-derived polio paralysis was reported in an unvaccinated individual in New York in 2022.

Public health officials emphasize the importance of building trust through ongoing dialogue with communities, healthcare providers, and local leaders to address concerns and combat vaccine hesitancy. Continued vigilance and concerted immunization efforts remain vital to achieving and sustaining global polio eradication.