On April 26, 1954, the first effective polio vaccine developed by Jonas Salk was used in one of America's largest medical experiments held in the 1950s.
The experimental polio vaccine study led by Thomas Francis involved the inoculation of around 4,000 children at Franklin Sherman Elementary School in McLean, Virginia. By the conclusion of the study, roughly 440,000 children in 44 states from Maine to California received at least one injection of the polio vaccine.
One year later, the results of the experimental Salk polio study found the vaccine to be at least 60-90 percent effective against the polio strains. Soon after, in a global effort to eradicate polio, more effective and potent vaccines were developed. By the end of the 20th century, polio disease has been officially eliminated in major parts of the world.