Smallpox

Health

How Long Does a Smallpox Vaccine Last?

How does the smallpox vaccine work? The smallpox vaccine is made from a virus called vaccinia, which is a relative of the smallpox virus. The vaccine contains live vaccinia virus that has been weakened so that it cannot cause smallpox in a healthy person. When the vaccine is given, the weakened virus enters the body and stimulates the immune system…