Smallpox Vaccine Scar: A Historical Marker

Many people have a small, round scar on their upper arm from the smallpox vaccine, commonly administered before the 1970s. This vaccine used the live Vaccinia virus to trigger immunity against the deadly Variola virus, which caused smallpox.

“After receiving the shot, blisters appear at the injection site, which eventually heal and leave a circular scar,” says the original article.

The scar forms because the needle pricks each delivered a bit of the vaccine, causing blisters. Initially, the injection site swells briefly, then returns to normal. However, 6 to 8 weeks later, a lump forms, resembling a mosquito bite, which grows into a tumor, oozes fluid, and eventually heals into a permanent scar.

By the early 1970s, smallpox was eradicated in most of the Western world, and vaccinations ceased in the 1980s due to the lack of exposure to the Variola virus. The scar remains a historical reminder of a once-dangerous disease.