There was no treatment for smallpox. It was fatal in about 3 in every 10 people who caught it. The disease was wiped out through vaccination. Vaccination (introducing material under the skin to protect against disease) was developed after an 18th-century doctor, Edward Jenner, noticed that milkmaids hardly ever caught smallpox. He guessed it was because they were protected by being exposed to another mild disease, cowpox. Jenner deliberately infected his gardener’s son with cowpox and then showed he was immune to repeated exposure to smallpox.