Which type of immunity is primarily stimulated by live attenuated vaccines?

• A. Passive immunity
• B. Innate immunity
• C. Cellular immunity
• D. Adaptive immunity

Answer: (D)

Live attenuated vaccines are designed to mimic a natural infection by using a weakened form of the pathogen. This results in the body mounting an immune response similar to what would occur during a natural infection. Specifically, live attenuated vaccines stimulate adaptive immunity, which is the immunity developed over time through exposure to specific pathogens.

Adaptive immunity involves both humoral (B cell-mediated) and cellular (T cell-mediated) responses. When a live attenuated vaccine is administered, the immune system generates a robust response, activating lymphocytes that can remember the pathogen. This memory leads to a more efficient and rapid response upon subsequent exposures to the actual pathogen.

In contrast, while passive immunity involves the transfer of antibodies from another source and innate immunity is the body’s first line of defense that does not involve specific recognition of pathogens, they do not invoke the same long-lasting, specific immune response that is characteristic of adaptive immunity. Thus, the principal type of immunity stimulated by live attenuated vaccines is indeed adaptive immunity, making this answer correct.