Which statement best describes passive immunity?

Which statement best describes passive immunity?

• A. Immunity produced by a person's own immune system; long lasting
• B. Transfer of antibodies produced by one person or animal to another; short immunity
• C. Immunity from a vaccine-induced response
• D. Immunity that lasts a lifetime

Answer: (B)

Passive immunity involves the transfer of antibodies produced by one person or animal to another. This provides immediate protection but is short-lived because the recipient’s immune system hasn’t produced its own antibodies or memory cells, so once the borrowed antibodies degrade, protection fades. Examples include maternal antibodies passed to a fetus across the placenta or through breast milk, and administration of prepared antibodies (immune globulin). In contrast, active immunity requires the individual’s own immune system to respond and generate memory, such as after infection or vaccination, leading to longer-lasting protection.

Passive immunity involves the transfer of antibodies produced by one person or animal to another. This provides immediate protection but is short-lived because the recipient’s immune system hasn’t produced its own antibodies or memory cells, so once the borrowed antibodies degrade, protection fades. Examples include maternal antibodies passed to a fetus across the placenta or through breast milk, and administration of prepared antibodies (immune globulin). In contrast, active immunity requires the individual’s own immune system to respond and generate memory, such as after infection or vaccination, leading to longer-lasting protection.