How do vaccines function in the immune system?

Vaccines function by stimulating the immune system to recognize and fight specific pathogens. When a vaccine is introduced into the body, it typically contains a harmless part or a weakened form of a virus or bacterium, which prompts the immune system to respond without causing the disease. This response includes the activation of immune cells and the production of antibodies tailored to recognize the specific pathogen.

Once the immune system has been primed through vaccination, it retains a memory of the pathogen. In the event of future exposure to that pathogen, the immune system can quickly and effectively mobilize its defense mechanisms, providing immunity and often preventing illness. This process is essential for an effective immune response and is the foundation of how vaccines confer protection against infectious diseases.