Michael Specter chronicles the gory history of vaccination:
By 1700, variolation—deliberate infection with smallpox—had been tried successfully as a preventive measure. It was dangerous, but far less so than the disease itself. Dried smallpox scabs were blown into the nose of an individual, who then contracted a mild form of the disease but was immune afterward. … The actual vaccine—the world’s first—was invented by Edward Jenner, a British country doctor, at the end of the eighteenth century. After noting that milkmaids rarely got the disease, he theorized, correctly, that exposure to cowpox—a virus similar to smallpox but much less virulent—conferred resistance.
The Dish 