December 9
https://www.history.com/this-day-in-history/december-9
On December 9, 1979, a commission of scientists declare smallpox has been eradicated. The disease, which carries around a 30 percent chance of death for those who contract it, is the only infectious disease afflicting humans that has officially been eradicated.
Something similar to smallpox had ravaged humanity for thousands of years, with the earliest known description appearing in Indian accounts from the 2nd century BCE. It was believed that the Egyptian Pharaoh Ramses V died of smallpox in 1145 BCE; however, recent research indicates that the actual smallpox virus may have evolved as late as 1580 CE. A type of inoculation—introducing a small amount of the disease in order to bring on a mild case that results in immunity—was widespread in China by the 16th century.