Smallpox was one of the deadliest diseases in human history. It’s believed to have been around for at least 3,000 years and it killed millions. Then an English doctor named Edward Jenner noticed something everyone else had missed. Milkmaids who’d already caught cowpox didn’t catch smallpox. In 1796 he showed that a similar inoculation could protect other people, and the first successful vaccine was born. It took a long time, but in 1967 the World Health Organization launched an all-out push to wipe the disease out. The last known natural case was in Somalia in 1977, and in 1980 smallpox was declared eradicated. One careful observation, followed by years of faithful teamwork, ended an ancient killer.
