When the results of those studies showed the vaccine to be safe and effective in 1955, church bells rang. Loudspeakers in stores, offices and factories blared the news. People crowded around radios. "There was jubilation," says Stewart. People couldn't wait to sign their kids up for a shot.
Then tragedy struck. One of the six labs manufacturing the vaccine, Cutter Laboratories in Berkeley, Calif., made a terrible mistake. The correct list of ingredients for the Salk vaccine called for polio virus that had been inactivated, but in the Cutter facility, the process of killing the virus proved defective. As a result, batches of the company's vaccine went out that mistakenly contained active polio virus. Of the 200,000 children who received the defective vaccine, 40,000 got polio from it; 200 were left with varying degrees of paralysis, and 10 died.