Jonas Salk: He Put An End To Polio

Not quite 50 years after the Salk vaccine was created, polio in America is a terror of the past. But in the '50s, tens of thousands of people -- mostly children -- fell victim to the disease every year. Come summer, when polio hit hardest, newscasts carried the day's tally of new cases. Parents were afraid to let children swim in public pools or go to the movies.

No wonder Dr. Jonas Salk, developer of the first polio vaccine, became a revered name. While the science that laid the foundation for the vaccine was done by others, it was Salk who moved with lightning speed to develop and test it. As he relentlessly perfected the vaccine, he had to face down critics who argued that his approach, which used an inactivated rather than weakened form of the virus, was flawed. "Taking a live infectious agent and rendering it into a safe vaccine was just a tremendous piece of work," says Emilio A. Emini of the International AIDS Vaccine Initiative.