The body’s ability to recognize, respond to, and defend against harmful foreign substances and infectious agents.
Immunity involves multiple components of the immune system, including physical barriers, innate immune responses, antibodies, and specialized immune cells. Protection can develop through previous infection, vaccination, transfer of antibodies from another person, or other biological mechanisms.
Immunity is not always complete or permanent. Its strength and duration can vary depending on the infectious agent, the type of immune response, and the person’s circumstances.
QUICK FACT
Having immunity does not always mean a person can never become infected. In some situations, immunity mainly reduces the likelihood of severe disease, the amount of infection, or the duration of illness.
COMMONLY CONFUSED WITH
Immune system: The immune system is the collection of cells, tissues, organs, and molecules involved in defense; immunity is the resulting capacity to recognize and respond to threats.
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