Who discovered the smallpox vaccine?

Edward Jenner discovered the smallpox vaccine. In 1796, the English physician tested the idea that infection with cowpox could protect people from the far more dangerous smallpox. He took material from a cowpox sore on milkmaid Sarah Nelmes and inoculated James Phipps, the eight-year-old son of his gardener.

Phipps developed a mild reaction but did not contract smallpox when Jenner later exposed him to the disease. Jenner published his findings in 1798, helping establish vaccination as a safer alternative to variolation, an older practice that deliberately exposed people to smallpox and carried serious risks.

Jenner did not invent the broader idea of inoculation. Variolation had been practiced for centuries in parts of Asia and Africa and was introduced to Britain by Lady Mary Wortley Montagu. Jenner’s achievement was demonstrating and popularizing protection through cowpox. The word “vaccine” comes from vacca, the Latin word for cow.

Smallpox was eventually eradicated through international vaccination campaigns; the World Health Organization declared it eradicated in 1980.