Polio is ancient, from Egyptian art showing withered limbs to a 4,000-year-old skeleton in the United Arab Emirates, yet its great epidemics came in the 20th century. The episode explains why: for most of history infants met the virus while still protected by maternal antibodies, and modern sanitation delayed that first exposure until children were older and far more likely to be paralyzed. About 75 percent of infections cause no symptoms and only a small fraction reach the motor neurons, so silent carriers spread it widely. In the United States the 1952 epidemic brought nearly 58,000 cases, more than 3,000 deaths and over 21,000 people left with some paralysis.

When bulbar polio stopped patients breathing and iron lungs ran out during a 1952 outbreak in Copenhagen, anesthesiologist Bjorn Ibsen used tracheostomies and hundreds of medical students squeezing bags by hand, the forerunner of the modern intensive care unit. The hosts then compare Jonas Salk’s killed injected vaccine with Albert Sabin’s live oral drops, follow the Global Polio Eradication Initiative, and explain how vaccine-derived strains came to outnumber wild polio.

• Why paralysis risk climbs from about one in a thousand young children to one in 75 adults
• William Hammond’s 1950 trial using gamma globulin from survivors, about 80 percent effective against paralysis
• Salk’s vaccine as homeland defense and Sabin’s as border patrol in the gut
• From roughly 350,000 paralyzed children in 1988 to 30 wild cases in 2022, with wild virus endemic only in Pakistan and Afghanistan
• The fake hepatitis B vaccination campaign that damaged trust, and the genetically stabilized nOPV2 licensed by WHO in December 2023