Immunization, process of becoming, or rendering a body, resistant to a particular disease. Immunization occurs naturally when disease antibodies develop through exposure or are passed from mother to fetus or nursing child, but the term generally refers to the medical procedure of administering vaccines or serums. Vaccines activate the production of antibodies by introduction into the bloodstream of germs, toxins, etc. (active immunization). Serums contain antibodies produced by another body (passive immunization) and provide only temporary immunity. The first method of immunization was Edward Jenner's smallpox vaccine (1796). Immunization should be performed in children for at least 5 dangerous diseases: whooping cough (pertussis), diphtheria, tetanus, poliomyelitis, and measles. Due to immunization, many serious diseases are now rare.
See also: Immunity.