Edward Jenner, an English country doctor, invented vaccination in 1796: hearing that milkmaids who caught cowpox never got smallpox, he inoculated eight-year-old James Phipps with cowpox matter on 14 May 1796 and later exposed him to smallpox — the boy stayed healthy. Louis Pasteur gave the method its science and its name in the 1880s.
Smallpox killed roughly a third of its victims and scarred the rest; it is estimated to have killed 300 million people in the twentieth century alone. Jenner's insight — that a mild related disease could train the body against a killer — turned folk wisdom into the most life-saving medical technology ever devised. In 1980 the World Health Organization declared smallpox eradicated: the first and only human disease ever wiped out.
