21. Edward Jenner and smallpox
Edward Jenner gave the world the words vaccine and vaccination, developed from the term he created for smallpox of the cow, Variolae vaccinae to describe cowpox. In 1798, Jenner produced a work he titled Inquiry into the Variolae vaccinae known as the Cow Pox, in which he described his finding that cowpox protected against the more lethal smallpox. Smallpox was lethal indeed in Jenner’s day, killing up to 10% of the British population annually, with localized outbreaks often reaching death rates as high as 20%. Other British physicians observed that cowpox appeared to protect against smallpox before Jenner, and inoculation was practiced by some before he did (using weakened smallpox), but Jenner made the procedure widespread. He noted the commonly accepted phenomenon that milkmaids often did not develop smallpox during outbreaks.
Jenner postulated the milkmaids were exposed to pus from the blisters caused by cowpox on the cows they milked, and were thus immunized from smallpox. Jenner scraped pus from the hands of a milkmaid with cowpox and inoculated the eight-year-old son of his gardener. He later injected the boy with weakened smallpox virus, the standard method of immunization at the time. The boy should have reacted with a weak case of smallpox, but no smallpox presented at all. Despite initial resistance from the medical community, eventually, inoculation using smallpox was banned and in 1840 the British government authorized the free distribution of inoculation using cowpox. In 1979 the World Health Organization listed smallpox as an eradicated disease. The world no longer needs to fear smallpox outbreaks.