What is the name of the first successful vaccine, developed by Edward Jenner?

The first successful vaccine developed by Edward Jenner was the smallpox vaccine.

Jenner’s breakthrough grew from the observation that milkmaids who had caught cowpox appeared to be protected from smallpox. On 14 May 1796, he inoculated eight-year-old James Phipps with material from a cowpox lesion. Phipps later resisted deliberate exposure to smallpox, supporting Jenner’s theory.

Jenner published his findings in 1798 in An Inquiry into the Causes and Effects of the Variolae Vaccinae, a work that helped establish vaccination as a medical practice. The word vaccine comes from vaccinia, related to vacca, the Latin word for cow. His method used cowpox or a closely related virus to train immunity against smallpox.

Smallpox vaccination was not the same as variolation, an older and riskier practice that exposed people to smallpox material. Jenner’s approach became the foundation of modern immunization. After a worldwide campaign led by the World Health Organization, smallpox was declared eradicated in 1980.