vaccine /vaksēn′, vak″sēn, -sin/ [L, vaccinus] , a suspension of attenuated or killed microorganisms administered intradermally, intramuscularly, orally, or subcutaneously to induce active immunity to infectious disease. Viruses and rickettsia used in some vaccines are grown in avian embryos, rabbit brain tissue, or monkey kidney tissue, and the organisms are usually inactivated by formalin, phenol, or beta-propiolactone. Bacteria for some vaccines may be inactivated by acetone, formalin, heat, or phenol. Vaccines may be used as single agents or in combinations. Compare antiserum.
