A vaccine is a substance given to stimulate the body's immune system to protect against a particular disease. It typically has a small, weakened, or a non-active part of the virus or bacteria that causes the disease. When a person receives a vaccine, their immune system recognizes the foreign substance as a threat and produces antibodies to fight it. This process prepares the immune system to respond quickly if the person is exposed to the disease-causing organism in the future, preventing illness or reducing its intensity.

What is a "vaccine"?

“vaccine”的英语定义和含义

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