When I was a child, I noticed a small circular scar on my mother’s upper arm and always wondered about it. Years later, I saw the exact same mark on an elderly woman while helping her off a train. The shape and placement felt strangely familiar, bringing back that childhood memory. Curious, I later asked my mother about it, trying to understand what I had seen on both people.

She explained it was from a smallpox vaccination, something commonly given decades ago before the disease was eradicated worldwide. Many people of her generation still carry this mark. It was a routine part of public health before smallpox disappeared completely through global immunization efforts led by health organizations.

Smallpox was once a deadly infectious disease caused by the variola virus, spreading easily between people and often causing fever, rash, and painful pustules. In severe cases it could be fatal and left many survivors with permanent scars. It was one of the most dangerous diseases in history before vaccination programs controlled and eventually eliminated it.

The vaccine used a live vaccinia virus and was given with a special multiple-puncture needle, which created a local skin reaction that formed a blister and then a scab. As it healed, it often left a small circular scar. Today, that mark is a reminder of one of medicine’s greatest achievements and a time when humanity successfully eradicated a global disease.