In what year was the last natural case of smallpox documented?

The story behind the answer

1977 is correct because the last naturally occurring case of smallpox (variola minor) was documented that year in Somalia, in a man named Ali Maow Maalin. After that, the disease no longer spread in the wild. A lab accident in 1978 caused a final death, and the World Health Organization officially certified smallpox eradicated in 1980.

Context that helps: smallpox is the first human disease ever eradicated, thanks to a global WHO campaign using ring vaccination—quickly vaccinating contacts around each detected case to stop transmission. Memory tip: think “lucky sevens stopped the pox”—1977 ends natural cases; “’80 = officially zero” marks the eradication certification.