immunization
(im″u-nĭ-za´shәn)
the process of making a person immune, or of becoming immune. Called also inoculation and vaccination.
active immunization
stimulation with a specific antigen to cause antibodies to be formed in the body. The antigen may be in one of four forms: (1) dead bacteria, as in typhoid fever immunization; (2) dead viruses, as in the Salk vaccine; (3) live attenuated (weakened) viruses, as in Sabin vaccine; and (4) toxoids (altered forms of toxins produced by bacteria), as in immunization against tetanus and diphtheria. Because active immunization causes the body to produce its own antibodies and to go on producing them, protection against
disease will last several years, in some cases for life.
passive immunization
temporary immunization produced introducing pre-formed antibodies or sensitized lymphoid cells into the body. The person who has been immunized is protected only as long as these antibodies remain in the blood and are
active, usually from 4 to 6 weeks.
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