Edward Jenner Vaccinated an 8-Year-Old in 1796 and Tested It by Injecting Smallpox Six Weeks Later

Edward Jenner was a country physician in Berkeley, Gloucestershire, in the 1790s, in a region where smallpox killed roughly one in ten people in his own lifetime — and as many as one in five in dense urban areas. Folk knowledge among English dairy workers held that milkmaids who had caught cowpox, a milder pox virus from cattle, did not get smallpox afterward. Jenner had been thinking about this since his medical apprenticeship.

On May 14, 1796, he carried out his test. He took fresh pus from a cowpox lesion on the hand of a milkmaid named Sarah Nelmes, who had picked up the infection from a cow named Blossom, and scratched it into the arm of an eight-year-old boy named James Phipps, the son of his gardener. Phipps developed a mild fever and the local sore. He was ill for about a week and recovered fully. Six weeks later, on July 1, Jenner repeated the procedure with material from a fresh case of smallpox. The boy did not get sick. He was immune. Jenner repeated the experiment on him twenty more times over the next several years, with the same result.

Jenner published his results privately in 1798 after the Royal Society declined to print them and called the new procedure "vaccination," from Latin vacca — cow. Within a decade vaccination had spread across Europe; Napoleon, then at war with Britain, ordered his troops vaccinated and sent Jenner a medal in 1804, saying he could not refuse anything to one of the greatest benefactors of mankind. The World Health Organization declared smallpox eradicated worldwide in 1980 — the only time in human history the species has eliminated one of its own diseases.