When I was a child, I noticed a peculiar scar on my mother’s upper arm — a ring of small indents surrounding a larger one. It fascinated me, but like many childhood curiosities, I eventually forgot about it. Years later, while helping an elderly woman off a train, I noticed the same type of scar in the same spot. My curiosity returned instantly. When I asked my mother about it, her answer surprised me: it was from the smallpox vaccine.

Smallpox was a deadly viral disease caused by the variola virus. It spread easily and killed roughly 30% of those infected, leaving survivors permanently scarred. For centuries, it devastated populations worldwide.

Thanks to global vaccination campaigns, smallpox became the first disease eradicated by humanity. The World Health Organization declared it eradicated in 1980, and routine vaccinations in the U.S. had already stopped in 1972.

The smallpox vaccine was unique. Using a bifurcated needle — a small two-pronged instrument dipped into the vaccine — the skin was pricked multiple times, introducing a live but far less dangerous virus called vaccinia. After vaccination, a blister formed, scabbed, and healed, leaving behind the distinctive circular scar recognized globally.

For many, that scar became a symbol of protection — a visible reminder of immunity against one of history’s deadliest diseases. Today, few people under 50 bear the mark, as smallpox vaccination is no longer necessary.

The eradication of smallpox stands as one of humanity’s greatest medical victories. Those who still carry the smallpox scar bear a living piece of history — proof of science’s triumph over a once-unstoppable killer.