In the 1954 Salk field trial, the experimental vaccine aimed to prevent polio.
The trial tested Jonas Salk’s inactivated poliovirus vaccine, commonly called IPV. The vaccine used virus particles that had been chemically inactivated, so they could stimulate immunity without causing poliomyelitis.
More than 1.8 million children participated in the large United States trial, making it one of the biggest medical field studies of its time. Results announced in 1955 showed strong protection against paralytic disease, and the vaccine was licensed that year.
Polio is caused by poliovirus and can invade the nervous system, sometimes causing permanent paralysis. Salk’s vaccine differs from Albert Sabin’s later oral vaccine, which uses live attenuated virus. Both vaccines played major roles in reducing polio worldwide.