Have you ever wondered why some people have a tiny round scar on their upper left arm? This is commonly known for people who were vaccinated for smallpox. This vaccine was very common before the 70s. Doctors used a live Vaccinia virusin order to trigger an immune response that would protect people from the Variola virus that caused smallpox.
Scarring
After the vaccination was done, blisters formed and afterwards, they developed a crust and healed in several weeks. In the end, there was a round scar left. The doctors used a bifurcated needle dipped into the Vaccinia solution to deliver the vaccine. The individual’s arm was poked few times and each time the needle broke the skin, a tiny amount of the vaccine was inserted, which caused blistering. This is probably why the scars are rather large.