On 26 April 1954, the largest clinical trial in medical history was launched in New York City by the National Foundation for Infant Paralysis (NFIP). It was the testing of a vaccine against polio, which was discovered by Jonas Edward Salk.

Salk had worked on the vaccine for several years, employing methods developed by John Enders at Havard University. The vaccine is actually the polio virus itself, but treated to make it unable to pass on the disease, while allowing the body to build up immunity against polio.

Salk, however, was apprehensive about the mass trial. A similar trial in 1935, gave healthy children polio, killing six of them. The virologist had tested the vaccine on some children, including his three sons, but was still unsure about the vaccine. "When you inoculate children with a polio vaccine, you don’t sleep well for two or three months."

However, the NFIP, founded by US President Franklin Roosevelt (himself paralysed by polio), went ahead with vaccinating 1.8 million children across 44 states, at a cost of $7.5 million. This marked the end for a disease that affected tens of thousands of children every year.