To induce an immune response that would shield humans from the dangerous Variola virus that caused smallpox, live Vaccinia virus was utilized.
Blisters develop at the injection site after receiving a shot. Within a few weeks, the blisters heal and form a crust.

The final end has a circular scar. Each time the needle pierced the skin, a tiny amount of the vaccine was applied, and blisters developed. The scars are so evident because of this.
The area where the shot was administered expands slightly immediately and over the following 6 to 8 hours.

After that, the edema goes away and the injection site seems normal. After 6 to 8 weeks, a lump that resembles a mosquito bite returns.
It begins to grow and develop into a tumor. It eventually cracks open, starts to seep fluid, and develops into an ulcer.

A scar develops as the sore mends. It takes two to five weeks to complete. The process of ulceration and healing may occur two or three times. It created a scar that will never heal.
After the early 1970s, smallpox was eradicated in the vast majority of the Western world. They did not need to get immunized unless they were traveling to an area where the virus was still present.

As it recovers, a scar forms. Finishing the procedure takes two to five weeks. The ulcers may develop and heal twice or three times. The scar that develops is irreversible.
Smallpox had largely disappeared from the Western world by the early 1970s. They did not need to get immunized unless they were traveling to an area where the virus was still present.