Do you have COVID-19 questions? Our scientists have answers.

How do vaccines work?

Vaccines work by stimulating a person’s immune system to develop protections against a disease.

Sometimes getting a vaccine can lead to mild health impacts, such as a fever. The CDC advises that such minor symptoms are normal and should be expected as the body builds immunity.

Different vaccines can work in different ways and each way has its advantages and disadvantages. For example, some require just one dose and others may require multiple doses to be given. Further, vaccines that work by giving people a weakened form of the virus, which for most people causes no more than mild, if any, illness, may not be suitable for people with weakened immune systems. The CDC encourages people to talk with their doctor to decide what vaccinations are right for them.

For more detailed information about how vaccines work, check out this resource from the CDC.

Updated: 20 October 2020

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