What is a vaccine?

A vaccine is defined as a biological preparation that provides active acquired immunity to a specific infectious disease. This is achieved by introducing a harmless component of the pathogen (such as an inactivated toxin, an attenuated microorganism, or a piece of the pathogen's genetic material) into the body. This triggers the immune system to recognize the component as foreign, enabling it to produce an immune response, which includes the generation of memory cells. These memory cells remain in the body and provide long-term protection, allowing the immune system to respond more efficiently and effectively if exposed to the actual pathogen in the future.

In contrast, other options refer to different medical interventions. Treatment for chronic diseases typically involves ongoing management strategies rather than immunization, antibiotics are specific medications that treat bacterial infections and do not provide immunity, and genetic therapies focus on correcting genetic disorders by altering genes but do not act as vaccines. Thus, the distinction lies in the specific role and mechanism of vaccines in inducing immunity compared to these other medical approaches.