On this day, April 26, in 1954, Jonas Salk’s polio vaccine began field trials.

“The polio vaccine field trials of 1954, sponsored by the National Foundation for Infantile Paralysis (March of Dimes), are among the largest and most publicized clinical trials ever undertaken. Across the United States, 623 972 schoolchildren were injected with vaccine or placebo, and more than a million others participated as “observed” controls. The results, announced in 1955, showed good statistical evidence that Jonas Salk’s killed virus preparation was 80-90% effective in preventing paralytic poliomyelitis.” – National Institutes of Health.

President Franklin Roosevelt was diagnosed with polio in 1921 at the age of 39 and was left paralyzed from the waist down. He helped found the National Foundation for Infantile Paralysis, in 1938.

Karsh photographed Jonas Salk in 1956 and 1991. See more.