Many individuals received this vaccination before the 1970s, a critical measure taken to safeguard against the perilous Variola virus that once caused smallpox.
This vaccine employed a live Vaccinia virus to provoke a protective immune response. Following the shot, blisters would emerge at the injection site. Over a few weeks, these blisters would heal and form a characteristic crust, leaving behind a circular scar. The distinctiveness of these scars is attributed to the minuscule quantities of vaccine deposited each time the needle punctured the skin, inducing blister formation.
Immediately after the shot, the administered area would slightly expand, and this effect would persist for the next 6 to 8 hours. Subsequently, the edema would subside, returning the injection site to its normal appearance. Around 6 to 8 weeks later, a lump akin to a mosquito bite would reappear. This lump would grow and eventually transform into a tumor. As it progressed, the tumor would rupture, exude fluid, and eventually develop into an ulcer. As the ulcer healed, a scar would take form, a process requiring two to five weeks. This cycle of ulceration and healing might occur two or three times, resulting in a permanent scar.
By the early 1970s, smallpox had largely been eradicated in the Western world. Consequently, vaccination was not required unless individuals were traveling to regions where the virus still posed a threat. The scar, however, served as a lasting reminder of the importance of smallpox vaccination.
In the 1980s, as the risk of exposure to the Variola virus diminished, smallpox vaccinations were completely phased out, marking the end of an era in which these distinctive scars were routinely acquired.