Smallpox vaccine is live vaccinia (cowpox) virus grown onthe skin of a bovine calf. Smallpox is a highly lethal and disfiguringdisease that was common throughout history.Smallpox vaccine was used routinely in the United Statesbut today is no longer recommended. (There have been noreported cases of smallpox since the 1940s.) In 1982, smallpoxwas declared eradicated worldwide. With smallpox, therisks of the vaccine outweigh the benefits; the vaccine penetratesthe central nervous system and potentially fatal encephalitisoccurs in 1 of 105 patients. After exposure tosmallpox, the vaccine can be injected to lessen the severityof the disease.
