A lot of people have a small, round scar on their upper arm from the smallpox vaccine they got before the 1970s. This vaccine used a live virus to help the body fight against the dangerous virus that caused smallpox.

The original article states that after getting the shot, blisters show up where the injection was given. These blisters will heal over time and leave a round scar.

The marks are easy to see because each time the needle was used, a small amount of the vaccine was injected, creating blisters.

The place where the shot was given may get a little swollen for a short time, but it will go back to normal.

However, after 6 to 8 weeks, a bump appears that looks like a mosquito bite and develops into a lump. Later on, it opens up, leaks liquid, and turns into a sore, which eventually heals and becomes a permanent scar.

Smallpox was eliminated in most of the Western world by the early 1970s. Vaccinations stopped in the 1980s because people were no longer at risk of getting the Variola virus.

The mark is a reminder of a disease that was once very dangerous.