On October 26, 1977, in Merca, a port town on the Somali coast, a hospital cook named Ali Maow Maalin woke with a fever and a rash. It was smallpox — a virus that for centuries had killed up to half of those it struck. But this case was unlike any before it: it would prove to be the last naturally occurring case of smallpox the world would ever see. A global campaign of vaccination and containment, run by the World Health Organization, had chased the virus across the planet until it had nowhere left to go but this single town.

The response in Merca was total. Teams vaccinated everyone in the town, set up checkpoints on the roads, and searched house by house for any further sign of the disease. They found none — not one more person caught it. Maalin recovered, and in the years that followed he turned his own brush with history into service, helping vaccinate children against polio. In 1980, the WHO declared smallpox eradicated, closing the campaign that had ended in Merca.

That is why October 26 still matters. It is the day a disease that had haunted humanity for centuries met its end in a small Somali port town — proof that a disease can be beaten outright, when the world decides to finish the job.