Smallpox vaccination adverse reaction: An adverse event occurring after smallpox vaccination (vaccinia).
Smallpox vaccination is a relatively safe, effective preventative against smallpox. However, in a number of individuals, smallpox vaccination can result in untoward effects and adverse reactions. Most are totally benign, if frightening in appearance. Some are serious, but treatable. A few, which rarely occur, are serious, life threatening and can be fatal.