Oh, thank you for responding. I might be wrong but mind if I ask if it could be from another vaccine?

The smallpox vaccine was commonly administered in the U.S. during the mid-20th century and often caused a small round scar as well. The BCG vaccine can also leave a similar mark, though it was not widely used in the U.S. at that time.

I'm suspecting these because every source I've checked says the chickenpox vaccine wasn't introduced until 1995. But of course, I'd be happy to be corrected if I'm mistaken.