As a child, I was oddly fascinated by a strange scar on my mother’s upper arm—a circular pattern of small indents surrounding a larger mark. I didn’t know why it caught my attention, and over time I forgot both the scar and my curiosity about it. Years later, that memory resurfaced unexpectedly when I helped an elderly woman off a train and noticed she had the exact same scar in the exact same place. The coincidence startled me. I couldn’t ask her about it, so instead I called my mother, who calmly reminded me she’d explained it many times before. The scar, she said, was from the smallpox vaccine—something so common in her generation that it barely registered as noteworthy, even though it once symbolized survival from a deadly disease.

Smallpox was one of history’s most terrifying viruses, killing nearly one in three infected people and leaving many survivors permanently scarred. Widespread vaccination campaigns in the mid-20th century changed everything, leading to the disease being declared eradicated in the United States by 1952, and routine vaccinations ending in the early 1970s. The vaccine was administered differently than modern shots, using a two-pronged needle to puncture the skin multiple times. This caused a localized infection that blistered, scabbed, and healed into a permanent scar—an unmistakable mark proving immunity. What once served as a silent badge of protection has now become a historical imprint on the skin, a reminder of a time when vaccines didn’t just prevent illness, but helped eliminate it entirely.