Which statement best defines active immunity?

Which statement best defines active immunity?

• A. Protection produced by a person's own immune system; lasts for many years
• B. Transfer of antibodies from another person or animal to another; short immunity
• C. Immunity generated by exposure to a pathogen that requires no immune response
• D. Temporary protection from a vaccine that fades quickly

Answer: (A)

Active immunity is protection produced by your own immune system in response to an antigen, leading to the development of memory cells that provide long-lasting protection. When your body encounters a pathogen or receives a vaccine, your B and T cells respond, generate antibodies, and form memory cells so future exposures are fought off more quickly and effectively, often for years or a lifetime. Vaccines are a classic way to create active immunity because they present the immune system with a safe form of the antigen and trigger this lasting adaptive response. The other descriptions miss a key point. Transferring antibodies from someone else or another animal gives passive immunity, which provides immediate protection but is temporary because the donor antibodies wane and your own immune system isn’t activated. The idea that immunity from pathogen exposure needs no immune response isn’t accurate; generating lasting immunity requires an immune response that creates memory. And vaccines aim for durable, not short-lived, protection, although some boosters may be needed over time.

Active immunity is protection produced by your own immune system in response to an antigen, leading to the development of memory cells that provide long-lasting protection. When your body encounters a pathogen or receives a vaccine, your B and T cells respond, generate antibodies, and form memory cells so future exposures are fought off more quickly and effectively, often for years or a lifetime. Vaccines are a classic way to create active immunity because they present the immune system with a safe form of the antigen and trigger this lasting adaptive response.

The other descriptions miss a key point. Transferring antibodies from someone else or another animal gives passive immunity, which provides immediate protection but is temporary because the donor antibodies wane and your own immune system isn’t activated. The idea that immunity from pathogen exposure needs no immune response isn’t accurate; generating lasting immunity requires an immune response that creates memory. And vaccines aim for durable, not short-lived, protection, although some boosters may be needed over time.