On May 14, 1796, English scientist and physician Edward Jenner inoculated 8-year old James Phipps with the world’s first vaccine against smallpox.

For many years, Jenner had heard the tales that dairymaids were protected from smallpox naturally after having suffered from cowpox. Jenner concluded that cowpox not only protected against smallpox but could be transmitted from one person to another as a deliberate mechanism of protection.

In early 1796, Jenner found a young dairymaid, Sarah Nelms, who had fresh cowpox lesions on her hands and arms, and used matter from Nelms’ lesions to inoculate Phipps. In July, Jenner inoculated the boy again, this time with matter from a fresh smallpox lesion. No disease developed.