Do you have a small, rounded scar on your upper arm? It’s likely from the smallpox vaccine, which was common before the 1970s.
The vaccine, using the live Vaccinia virus, triggered an immune response to protect against smallpox. After the shot, blisters formed at the injection site, eventually healing into a circular scar.
The process included swelling, blistering, and ulceration at the injection site, with the scar forming after several weeks of healing. By the early 1970s, smallpox was largely eradicated in the Western world, making the vaccine less common unless traveling to areas still at risk.
