World Polio Day is observed worldwide every October 24 to commemorate the birth of Jonas Salk, who developed the first effective polio vaccine. The observance was established by the nongovernmental organization Rotary International. Poliomyelitis has been known since ancient times, with its first clinical description provided by English physician Michael Underwood in 1789. The disease peaked in the 1950s, affecting children aged five to nine. Salk's inactivated vaccine, along with Albert Sabin's oral vaccine, played a crucial role in combating the virus, leading to the establishment of the Global Polio Eradication Initiative, which has reduced worldwide polio cases by 99%.