A type of immunity acquired by the transfer of antibody from one individual to another, such as from mother to offspring.
There are two ways to acquire passive immunity: (1) naturally acquired passive immunity and (2) artificially acquired passive immunity.
Passive immunity acquired naturally happens when a mother transfer antibodies to her offspring via placental route during pregnancy and via colostrum during breastfeeding.
Passive immunity acquired artificially is done by injecting antibodies or sensitized lymphocytes to an organism via a vaccination.
Compare: active immunity.