My Aunt Cecelia was just beginning the eighth grade when it happened.

In late spring 1951, she came home from school with a high temperature, feeling very ill. The next morning, her legs gave out as she tried to get out of bed. By that evening, she was so weak she could barely move.

She’d contracted polio.

In the 1940s and 1950s, polio infected thousands of children annually. In 1952 alone, nearly 60,000 were infected, leaving thousands paralyzed and more than 3,000 dead.

No one knew how polio...