any preparation used as a preventive inoculation to confer immunity against a specific disease, usually employing an innocuous form of the disease agent, as killed or weakened bacteria or viruses, to stimulate antibody production.
the virus of cowpox, used in vaccination, obtained from pox vesicles of a cow or person.
a software program that helps to protect against computer viruses, as by detecting them and warning the user.
A preparation of a weakened or killed pathogen, such as a bacterium or virus, or of a portion of the pathogen's structure that upon administration stimulates antibody production against the pathogen but is incapable of causing severe infection.
A vaccine prepared from the cowpox virus and inoculated against smallpox.
A preparation of a weakened or killed pathogen, such as a bacterium or virus, or of a portion of the pathogen's structure, that stimulates immune cells to recognize and attack it, especially through antibody production. Most vaccines are given orally or by intramuscular or subcutaneous injection. See Note at Jenner.
A Closer Look
In the 1950s, polio epidemics left thousands of children with permanent physical disabilities. Today, infants are given a vaccine to prevent infection with the polio virus. That vaccine, like most others, works by stimulating the body's immune system to produce antibodies that destroy pathogens. Scientists usually prepare vaccines by taking a sample of the pathogen and destroying or weakening it with heat or chemicals. The inactivated or attenuated pathogen loses its ability to cause serious illness but is still able to stimulate antibody production, thereby conferring immunity. The Salk polio vaccine contains killed virus, while the Sabin polio vaccine contains weakened live poliovirus. (Many scientists no longer consider viruses to be living organisms) Scientists are also able to change the structure of viruses and bacteria at the molecular level, altering DNA so that the potential of the vaccine to cause disease is decreased. New vaccines containing harmless bits of DNA have also been developed.
A substance prepared from dead or living microorganisms that is introduced into the body through inoculation. The vaccine causes the development of antibodies, which produce immunity to the disease caused by the microorganism.