It was not a scourge on the level of, say, the Black Plague of the early 1900s, but the Polio disease did afflict many all over the world. As populations in the United States and Europe greatly expanded by the end of the 19th and start of the 20th century, Polio virus outbreaks became regular summer events. For the United States, no better demonstration for the ravages of the disease could exist than the crippled president Franklin Roosevelt in a wheelchair.

On this day, February 23, in 1954, Dr. Jonas Salk, who developed the vaccine against the virus, began large-scale tests on the children in his hometown of Pittsburgh.

In effect, what Salk got was a city-wide clinical trial, some 15,000 children in all. With encouraging results from the Pittsburgh trial, Salk and his team at the University of Pittsburgh dramatically expanded the trial to 1.8 million children from the United States and Canada. In addition to being one of the largest field trials to date, it was the first one to use the double-blind method, where neither the researchers nor patients know whether they had the vaccine or a placebo.