What the small round scar on your arm might indicate

Scar Often Means: A Smallpox Vaccine Mark

For many adults born before the early 1970s in the United States (and in similar timeframes elsewhere), a small round scar on the upper arm can be a leftover mark from the smallpox vaccine. It’s one of those quiet “history stamps” some people carry without ever thinking about it.

Smallpox was once among the most continue reading …