1952, American History Museum
The first modern mass-inoculation campaign halted a fearsome scourge
Saying he’d be “personally responsible” for the results, physician Jonas Salk in 1952 injected his polio virus vaccine into children already stricken with the disease, along with himself, his wife and three sons. He’d grown the virus in test tubes of monkey kidney cells, then killed it with formaldehyde. His feat—“Salk Polio Vaccine Proves Success; Millions Will Be Immunized Soon,” The New York Times declared—helped arrest the contagious paralytic disease, which had terrified the world for decades.