It won't hurt if you don't look. The first vaccine against poliomyelitis was developed in the early 1950s by physician Jonas Salk, shown here injecting a young girl during a 1954 field test. The paralyzing virus had swept the U.S. from 1942-53, with its incidence peaking in 1950, when 33,344 cases were reported. Severe polio epidemics also occurred in Europe and Asia. Salk's vaccine, released in 1955, was based on three separate strains of a dead polio virus. Microbiologist Albert Sabin later developed an oral vaccine, based on a live but weakened virus, which was approved for use in the U.S. in 1960. Salk's vaccine has been used predominantly for mass vaccinations, while the oral vaccine typically has been given to infants. Because of rare instances of polio associated with the Sabin vaccine, however, the American Academy of Pediatrics in 1997 recommended expanded use of the Salk-type vaccine.

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"Jonas Salk and the Polio Vaccine"