Edward Jenner

Edward Jenner was born in 1749 in Berkeley, Gloucestershire, England, and died there in 1823. A country doctor, he had heard the folk observation that dairymaids who caught the mild disease cowpox seemed never to catch smallpox, one of the deadliest diseases of the era. On 14 May 1796 he tested the idea directly: he inoculated an eight-year-old boy, James Phipps, with matter from a cowpox sore on a milkmaid's hand, and weeks later deliberately exposed the boy to smallpox itself. Phipps did not develop the disease. Jenner published his findings in 1798, naming the technique vaccination after the Latin vacca for cow. The practice spread rapidly across Europe and the Americas despite real contemporary opposition, decades before anyone understood why it worked; germ theory and the science of immunology, which finally explained the mechanism, did not exist yet and would not for most of another century. Smallpox was declared eradicated worldwide by the World Health Organization in 1980, the only human disease eliminated this way to date, long after Jenner's own death.