Condensed from history.com. Click here for the full link.

On December 9, 1979, a commission of scientists declare smallpox has been eradicated. The disease is the only infectious disease afflicting humans that has officially been eradicated.

Something similar to smallpox had ravaged humanity for thousands of years. In 1796, the English scientist Edward Jenner discovered a vaccine. Unlike other types of inoculation, Jenner’s vaccine, made from a closely-related disease that affects cows, carried zero risk of transmission.

Many European countries and American states made the vaccination of infants mandatory, and incidents of smallpox declined over the 19th and early 20th centuries. Compared to other epidemic diseases, such as polio or malaria, smallpox eradication was relatively simple because the disease lives only in humans.

Starting in 1967, the World Health Organization undertook a worldwide effort to identify and stamp out the last remaining outbreaks of the disease. The last naturally-occurring case was diagnosed in Somalia in 1977. Two years later, doctors proclaimed its eradication. The elimination of smallpox is one of the major successes in the history of science and medicine.