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How Do Vaccines Help Your Body Fight Diseases?
疫苗如何帮助身体抵抗疾病？
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Vaccines contain weakened or dead germs, or just parts of them, that cannot cause serious illness.
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When injected, they teach your immune system to recognize dangerous invaders without making you sick.
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White blood cells quickly identify the vaccine material and produce special proteins called antibodies.
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Memory cells store this information so your body reacts faster if the real germ returns later.
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Some vaccines need booster shots because immunity fades slowly over many years.
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mRNA vaccines, like those for COVID-19, give cells instructions to build harmless virus pieces.
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This tricks the immune system into preparing defenses before actual infection occurs.
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Vaccines have helped wipe out diseases like smallpox and nearly ended polio worldwide.
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Herd immunity protects vulnerable people when enough community members are vaccinated.
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Doctors test vaccines many times to ensure they are both safe and strongly effective.