A vaccine is a biological preparation that helps to build immunity against a specific infectious disease. It typically contains a small amount or a weakened form of the disease-causing microorganism (such as a virus or bacterium) or parts of the microorganism, like proteins or sugars. These components, called antigens, stimulate the body's immune system to recognize and respond to the infectious agent without causing the disease itself.
When a person receives a vaccine, their immune system mounts a response by producing antibodies that can specifically recognize and neutralize the pathogen. This process also creates immunological memory, so if the person encounters the actual pathogen in the future, their immune system can quickly recognize and fight off the infection, preventing or reducing the severity of the disease.
Vaccines have been crucial in controlling and eradicating many infectious diseases, such as smallpox, polio, and measles. They have saved countless lives and improved public health worldwide.
GPT-4, 7 May 2023