Bacteria, viruses and other germs threaten your body every day. But when a disease-causing microorganism enters your body, your immune system mounts a defense, producing proteins called antibodies to fight off the invader. The goal of your immune system is to prevent illness by destroying the foreign invader or rendering it harmless.

Vaccines stimulate your body's immune system.
Vaccine-induced immunity results after you receive a vaccine. The vaccine triggers your immune system's infection-fighting ability and memory without exposure to the actual disease-producing germs. A vaccine contains a killed or weakened form or derivative of the infectious germ. When given to a healthy person, the vaccine triggers an immune response. The vaccine makes your body think that it's being invaded by a specific organism, and your immune system goes to work to destroy the invader and prevent it from infecting you again.
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