In the late 1700 s , as inoculation became more common in Europe and America, the death rate from smallpox declined. Epidemics still broke out, though, with large cities being hit especially hard.

The majority of victims were poor people, most of whom had not been inoculated. This started to change after a young country doctor named Edward Jenner developed a vaccine that would bring the scourge under control at last.

Young Edward Jenner

Edward Jenner was born in 1749 in Berkeley, a town in the English county of Gloucestershire. Jenner's parents died when he was five, and his older brother, Stephen, raised him. When a smallpox epidemic struck Gloucestershire in 1757, Jenner and several other children were inoculated by a local pharmacist. The pharmacist's technique, common at the time, was long and uncomfortable.

First, he prepared the children by bleeding them...