Set in 1762, the story, perhaps apocryphal, has it that an apothecary’s apprentice named Edward Jenner heard a dairy girl say, “I shall never have smallpox, for I have had cowpox. I shall never have an ugly, pockmarked face.” Perhaps he had overheard it from local folklore, for a “milkmaid’s milky skin” was a recurrent English meme. In May 1796, Jenner proposed a safer approach to smallpox vaccination. Cowpox, a virus related to smallpox, caused a far less severe form of the disease, with no deep pustules and no risk of death.
