Why would a vaccine be needed if we can do other things, like social distancing and wearing masks, to prevent the virus that causes COVID-19 from spreading?
Stopping a pandemic requires using all the tools available. Vaccines boost your immune system so it will be ready to fight the virus if you are exposed. Other steps, like masks and social distancing, help reduce your chance of being exposed to or spreading the virus. Together, COVID-19 vaccination and following CDC’s recommendations for how to protect yourself and others will offer the best protection from COVID-19.
See also: Treatments, vaccines, and immunity