“I got it five years before the vaccine,” Lang said, referring to the polio vaccine developed by Dr. Jonas Salk in the mid-1950s after an extensive clinical trial. The vaccine made Salk a national hero because, by the middle of the 20th Century, polio was every parent’s nightmare. The virus attacked the nervous systems of children and caused paralysis. It confined thousands to tank respirators known as iron lungs. In 1952, there were 57,879 cases, the worst year in U.S. history. Some 3,145 victims died that year and 20,000 were left disabled.