Before the 1970s, many people received the smallpox vaccine, which often left a permanent round scar on the upper arm. The vaccine used the live Vaccinia virus to create immunity against smallpox.
The process involved multiple needle punctures that introduced the vaccine into the skin, causing blisters to form. These blisters healed over 2–5 weeks, sometimes repeating the cycle, eventually leaving a scar.
Smallpox was eradicated in most of the Western world after the early 1970s, making vaccination unnecessary unless traveling to high-risk areas.