When Was the First Vaccine Created?

On 14 May 1796, English physician Edward Jenner took pus from a cowpox sore on the hand of dairymaid Sarah Nelmes and inoculated eight-year-old James Phipps. Six weeks later, Jenner exposed Phipps to smallpox, and the boy did not develop the disease. Jenner coined the term "vaccine" from "vacca" (Latin for cow). His work laid the foundation for immunology. Smallpox went on to kill an estimated 300 million people in the 20th century alone before being declared eradicated by the WHO in 1980 — the first human disease eliminated through vaccination.