Questions (and Answers) About Booster Shots for COVID-19 Vaccines

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What is the difference between an additional primary shot and a booster shot of a COVID-19 vaccine?

An additional primary shot is a third full dose of COVID-19 vaccine that is given 28 days after someone receives the standard two doses of either the Pfizer-BioNTech or Moderna COVID-19 vaccines. Only people who are moderately or severely immunocompromised should get an additional primary shot, and when they do, it should always be the same brand of the vaccine already received.

Booster shots can further enhance or restore protection that might have decreased over time after your primary series vaccination. They can be given to anyone age 5+ who has completed their primary vaccine series. The time frame for getting a booster depends on the type of COVID-19 shots originally received.

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Who needs an additional primary shot of a COVID-19 vaccine?

In general, additional shots are recommended for children and adults with moderately or severely weakened immune systems. If you think you need an additional primary shot, talk to your health care provider.

Who needs a booster COVID-19 vaccine?

Everyone 5+ who completes their COVID-19 primary vaccine series should now get at least one booster shot. The time frame for when to get this shot is different depending on which type of COVID-19 vaccine you originally received.

People 50+ and those 12+ who are immunocompromised are eligible for a second booster shot 4 months after they got their first booster, to increase their protection from severe COVID-19.

If I’m eligible for a COVID-19 vaccine booster, which type of vaccine should I receive?

For people 18+, CDC recommends Pfizer-BioNTech or Moderna (mRNA COVID-19 vaccines) as a booster dose in most situations. This includes people who received Johnson & Johnson’s Janssen COVID-19 vaccine (also called J&J/Janssen) for their primary vaccine dose. People who received the J&J/Janssen COVID-19 vaccine and got it again as a booster may get a booster of a Pfizer-BioNTech or Moderna COVID-19 vaccine at least 4 months later.

Children and teens ages 5 to 17 should receive a Pfizer-BioNTech booster.

Do I need a COVID-19 vaccine booster shot to protect me from COVID-19?

COVID-19 vaccines continue to protect people from getting seriously ill, being hospitalized, and even dying. However, research shows that there is some reduced protection over time against mild and moderate disease, especially among certain populations. A booster shot gives you even better protection, especially as more variants emerge.

Why are booster shots necessary if the COVID-19 vaccine is working like it should?

COVID-19 vaccines work well to prevent severe illness, hospitalization, and death. Clinical studies show that the ability of COVID-19 vaccines to protect you from initial infection and milder symptoms may decrease over time. This is something that happens with vaccines for many other illnesses, too. Studies have shown that getting a COVID-19 booster shot greatly increases your protection from a symptomatic COVID-19 infection. 

Why do some people who’ve been fully vaccinated still get sick with COVID-19?

Some people who are fully vaccinated will still get COVID-19 because no vaccines are 100% effective at preventing infection. Breakthrough infections are normal and expected. Even when fully vaccinated people develop symptoms, these symptoms are usually less severe, and the person is less likely to be hospitalized or die than if they were unvaccinated. This is because COVID-19 vaccines are still doing a very good job at preventing serious illness and death.

Updated: 6/14/2022