The administration of a vaccine to stimulate the host immune system to develop immunity (protection) against a specific pathogen or toxin. As of January 1999, vaccines are available for the following potential biological warfare agents: anthrax, Argentine hemorrhagic fever, botulinum toxin, plague, Q fever, Rift Valley Fever, smallpox, tularemia, Venezuelan equine encephalitis (VEE), and yellow fever. See also chemoprophylaxis; immunization.
The conferring of immunity through the introduction of an attenuated form of a virus; for example, the injection of cowpox virus to confer immunity to smallpox, or by the injection of a killed or inactivated virus. The principle is that the body, by learning to deal with a mild and harmless virus closely related to a more serious strain, or a dead or inactive virus, develops antibodies against the virulent, live or active virus