October 26th

On this day - 26th October 1977 - Smallpox was eradicated 

The Somali Ali Maow Maalin is the last human to have been naturally infected with (Variola Minor) smallpox. He contracted the disease on October 26th 1977. He survived, and the world health organisation declared the virus as officially eradicated two years later. Smallpox is believed to first have developed among humans around 10.000 BC. By the end of the 18th century died around 400.000 europeans annually. The eradication of this disease is considered one of the vaccination programs greatest success and 26th or October is by WHO considered the anniversary of the eradication of smallpox. 

Smallpox Vaccine