Which immunity type may provide protection immediately after exposure but wanes without prior exposure?

Which immunity type may provide protection immediately after exposure but wanes without prior exposure?

• A. Active immunity
• B. Natural immunity
• C. Adoptive immunity
• D. Passive immunity

Answer: (D)

Protection that is available immediately after exposure but fades without prior exposure is provided by passive immunity. In passive immunity, protective antibodies come from another person or from a therapeutic source rather than being produced by the recipient’s own immune system, so there’s no delay while the body mounts a response and no memory is formed. The protection is instant because antibodies are already present to neutralize the pathogen, but it wanes as these antibodies are cleared from the body over weeks to months if there’s no ongoing exposure or booster. Examples include maternal antibodies transferred to the fetus and through breast milk, or administration of immune globulins after exposure. By contrast, active immunity requires the body to respond to an antigen, takes time to develop, and provides longer-lasting protection due to memory formation.

Protection that is available immediately after exposure but fades without prior exposure is provided by passive immunity. In passive immunity, protective antibodies come from another person or from a therapeutic source rather than being produced by the recipient’s own immune system, so there’s no delay while the body mounts a response and no memory is formed. The protection is instant because antibodies are already present to neutralize the pathogen, but it wanes as these antibodies are cleared from the body over weeks to months if there’s no ongoing exposure or booster. Examples include maternal antibodies transferred to the fetus and through breast milk, or administration of immune globulins after exposure. By contrast, active immunity requires the body to respond to an antigen, takes time to develop, and provides longer-lasting protection due to memory formation.