If you have small round scar on the upper arm means that you are being vaccinated for small pox.
Before 1970s, this smallpox vaccine was common. For this vaccine was used live Vaccinia virus in order to trigger an immune response that would protect people against the dangerous Variola virus that caused smallpox.
After the vaccination, at the vaccination area were formed blisters, crusted over, and healed in a few weeks. Finally, it leaves a round scar.
In order to deliver the vaccine, it was used bifurcated needle which was dipped into the Vaccinia solution and the individual’s arm was poked several times. A small amount of the vaccine was deposited each time the needle broke the skin and blisters formed and that is the explanation why the scars are so large.
Right after the vaccine there appears a small swelling at the vaccination site which persists in a period of 6 – 8 hours. After that, the swelling disappears and the vaccination site looks normal. After 6 – 8 weeks swelling appears again which looks like a mosquito bite. Actually it starts to grow and forms a nodule which breaks open and discharges some fluid and forms an ulcer. The ulcer heals by forming a scar. This entire process lasts 2 – 5 weeks. There are times when this process of ulceration and healing recurs 2-3 times. The formed scar remains for lifetime.
Nowadays, the smallpox is no longer present in most of the Western world. To be more precise, after the early 1970’s there is no needed vaccination, unless a person was travelling to a country where the virus was still present.
It was certified that the Variola virus have been eradicated from the world’s population in 1980’s and this smallpox vaccination was stopped completely.