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The Naked Scientists Podcast · The Naked Scientists

Eradicating polio

March 10, 2026·31 min·3 clips
A man spent his entire 78-year life practicing law from inside an iron lung after contracting polio.
The Naked Scientists podcast examines the global effort to eradicate polio, a disease that once paralyzed hundreds of thousands annually. Polio is caused by three related viruses that infect only humans, making complete eradication theoretically possible. The disease primarily affects children, causing paralysis in about one in 200 infections, with severe cases requiring iron lungs for breathing support. Paul Alexander, who died recently at age 78, spent his entire life in an iron lung after contracting polio, even practicing law from within the device. The virus spreads through fecal-oral transmission, replicating in the intestines before potentially reaching the nervous system. Two types of vaccines currently exist: oral live vaccines that provide strong immunity and can spread person-to-person but risk reverting to dangerous forms, and killed vaccines that are safer but less effective at preventing transmission. Researchers at the University of Leeds have developed virus-like particle vaccines - empty viral shells that trigger immunity without containing genetic material, eliminating reversion risks while maintaining effectiveness. These new vaccines are also more temperature-stable, crucial for deployment in hot climates. Wild polio virus types 2 and 3 have already been certified eradicated globally, leaving only type 1 circulating in parts of Afghanistan and Pakistan. In 2024, 99 cases were reported from these regions, dropping to 44 cases so far in 2025. The remaining transmission occurs in three specific areas: Karachi, Pakistan; the Pakistan-Afghanistan border region; and southern Afghanistan, all facing security challenges that prevent consistent vaccination coverage. Countries like Yemen and northern Nigeria have successfully eliminated polio despite similar security challenges, providing hope for the remaining endemic areas. Surveillance continues through monitoring of acute flaccid paralysis cases and sewage testing for viral presence. The global effort has reduced daily polio cases from 1,000 in the 1980s to fewer than 50 annually today. However, political instability and conflict remain the biggest threats to final eradication, as the virus exploits vulnerable populations and fragmented health systems. Success requires sustained global cooperation in funding, science, and policy to cross the final meters of this marathon effort.

As heard by us

A clear look at why polio is nearly beaten, but not yet finished.

The episode treats polio as an active eradication problem, not a closed chapter. It lays out a disease that once caused paralysis and death on a huge scale, then follows the vaccines that pushed it to the brink and out of all but a handful of regions.

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Why you'd press play

You get the clearest path from vaccine science to why polio is still not history.

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