What Happened to Polio (Poliomyelitis)?
Poliomyelitis, commonly known as polio, is a highly infectious viral disease that can cause paralysis and death. Once a global scourge, widespread vaccination efforts led by the Global Polio Eradication Initiative (GPEI) have dramatically reduced cases by over 99%, eradicating two of the three wild poliovirus types. As of July 2026, wild poliovirus type 1 (WPV1) remains endemic in only two countries, Afghanistan and Pakistan, while outbreaks of circulating vaccine-derived poliovirus (cVDPV) continue to pose a significant challenge in under-immunized populations worldwide.
Quick Answer
Polio has been nearly eradicated globally due to extensive vaccination campaigns, with wild poliovirus type 2 and 3 officially eliminated. However, wild poliovirus type 1 (WPV1) persists in Afghanistan and Pakistan, which remain the only two endemic countries as of July 2026. A significant ongoing challenge is the emergence of circulating vaccine-derived poliovirus (cVDPV) outbreaks in areas with low immunization coverage, leading to new cases of paralysis in various countries, including recent detections in Africa. The Global Polio Eradication Initiative continues to implement strategies to interrupt all poliovirus transmission, facing hurdles like conflict, vaccine hesitancy, and funding gaps.
📊Key Facts
📅Complete Timeline16 events
Early Depictions of Polio-like Symptoms
Ancient Egyptian stele and carvings depict individuals with withered limbs, suggesting the presence of polio-like conditions for millennia.
First Clinical Description
British physician Dr. Michael Underwood provides the first known clinical description of polio, referring to it as 'debility of the lower extremities.'
Major Epidemics Emerge
Polio transforms from an endemic pathogen to a cause of widespread epidemics, particularly in industrialized countries, paralyzing hundreds of thousands of children annually.
Salk Polio Vaccine Licensed
Dr. Jonas Salk's inactivated polio vaccine (IPV) is announced as safe and effective, and subsequently licensed in the U.S., leading to mass immunization campaigns.
Sabin Oral Polio Vaccine Licensed
Dr. Albert Sabin's oral polio vaccine (OPV), using a live-attenuated virus, is licensed in the U.S. and becomes widely adopted due to its ease of administration and ability to induce community immunity.
Global Polio Eradication Initiative (GPEI) Launched
The WHO, Rotary International, UNICEF, and CDC launch the GPEI with the goal of eradicating polio globally by the year 2000, inspired by Rotary's pledge to immunize all children.
Americas Certified Polio-Free
The Region of the Americas is certified free of indigenous wild poliovirus, a significant milestone in global eradication efforts.
Western Pacific Region Certified Polio-Free
The WHO Western Pacific Region, including China, is certified polio-free, demonstrating successful interruption of wild poliovirus transmission.
Europe Certified Polio-Free
The WHO European Region is declared free of indigenous wild poliovirus, marking another major achievement in the global campaign.
Wild Poliovirus Type 2 (WPV2) Eradicated
Wild poliovirus type 2 is officially declared eradicated globally, with the last case detected in 1999.
Wild Poliovirus Type 3 (WPV3) Eradicated
Wild poliovirus type 3 is officially declared eradicated, with no cases detected since 2012.
African Region Certified Wild Poliovirus-Free
The WHO African Region is certified free of indigenous wild poliovirus after four years with no reported cases, a monumental achievement for the continent.
Vaccine-Derived Poliovirus Case in US
A case of vaccine-derived poliovirus (VDPV) is detected in an unvaccinated adult in New York, highlighting the risk of cVDPV in under-immunized populations even in polio-free regions.
Global Pledging Moment for Polio Eradication
A global pledging moment hosted in Abu Dhabi brings together governments, civil society, philanthropies, and partners to renew financial and political commitment to polio eradication.
GPEI Updates Outbreak Response SOPs
The Global Polio Eradication Initiative updates its outbreak response Standard Operating Procedures to sharpen detection, assessment, and response to poliovirus outbreaks, particularly focusing on cVDPV2.
Recent WPV1 Cases Reported in Endemic Countries
Afghanistan reports four new wild poliovirus type 1 (WPV1) cases, bringing its 2026 total to 11. Pakistan reports three WPV1 cases for 2026, with a total of 14 cases across both endemic countries as of July 2026.
🔍Deep Dive Analysis
Poliomyelitis, or polio, has afflicted humanity for millennia, with evidence dating back to ancient Egypt. The disease became a major public health crisis in the early 20th century, causing widespread epidemics of paralysis, particularly in industrialized nations. The development of effective vaccines marked a pivotal turning point in the fight against polio. Jonas Salk introduced the inactivated polio vaccine (IPV) in 1955, followed by Albert Sabin's oral polio vaccine (OPV) in 1961. These vaccines led to a dramatic decline in cases and the eventual elimination of wild poliovirus in many regions.
The Global Polio Eradication Initiative (GPEI) was launched in 1988 by the World Health Organization (WHO), Rotary International, UNICEF, and the U.S. Centers for Disease Control and Prevention (CDC), with the ambitious goal of global eradication. This initiative has achieved remarkable success, reducing polio cases by over 99% from an estimated 350,000 cases annually in 1988. The Americas were certified polio-free in 1994, followed by the Western Pacific Region in 2000, Europe in 2002, the South-East Asia Region in 2014, and the African Region in 2020. Wild poliovirus type 2 (WPV2) was declared eradicated in 2015, and wild poliovirus type 3 (WPV3) in 2019, leaving only WPV1 in circulation.
Despite these successes, the final stages of eradication have proven challenging. As of July 2026, wild poliovirus type 1 (WPV1) remains endemic only in Afghanistan and Pakistan. These countries face unique obstacles, including ongoing conflict, population displacement, weak health systems, vaccine hesitancy, and a ban on female community-based workers in some areas, which hinders vaccination efforts. The GPEI's Action Plan 2026 aimed to stop WPV1 transmission in these countries by June 2026, but cases continue to be reported. Afghanistan reported 11 WPV1 cases and Pakistan 3 WPV1 cases as of July 19, 2026.
Another significant hurdle is the rise of circulating vaccine-derived poliovirus (cVDPV) outbreaks. OPV, while highly effective, uses a weakened live virus that can, in rare instances and in under-immunized populations, mutate and regain its ability to cause paralysis. These outbreaks have been detected in various countries, including a case in the United States in July 2022 and ongoing cVDPV outbreaks in Africa and other regions in 2026, such as Chad, DR Congo, Ethiopia, Madagascar, and South Sudan. The GPEI has updated its outbreak response Standard Operating Procedures in July 2026 to address these evolving epidemiological challenges, with a particular focus on cVDPV2 outbreaks.
The global effort to eradicate polio also faces financial challenges, with a significant funding gap impacting campaigns. However, international commitment remains strong, with WHO Member States reaffirming their dedication to a polio-free future in February 2026. The strategy emphasizes strengthening routine immunization, timely detection of cases, and rapid response to outbreaks, while also planning for the transition of polio infrastructure to support broader public health priorities once eradication is achieved.
What If...?
Explore alternate histories. What if Polio (Poliomyelitis) made different choices?