What do I need to know about COVID-19 vaccine boosters?

The Food and Drug Administration (FDA) and the Centers for Disease Control and Prevention (CDC) have authorized Pfizer-BioNTech COVID-19 vaccine boosters for certain individuals.

Learn more about vaccine boosters

Who is eligible to receive a COVID-19 vaccine booster?

The Food and Drug Administration (FDA) and the Centers for Disease Control and Prevention (CDC) have authorized Pfizer-BioNTech COVID-19 vaccine boosters for certain individuals.

  • People 65 years and older and residents in long-term care settings should receive a booster shot of Pfizer-BioNTech’s COVID-19 vaccine at least 6 months after their Pfizer-BioNTech primary series,
  • People aged 50–64 years with underlying medical conditions should receive a booster shot of Pfizer-BioNTech’s COVID-19 vaccine at least 6 months after their Pfizer-BioNTech primary series,
  • People aged 18–49 years with underlying medical conditions may receive a booster shot of Pfizer-BioNTech’s COVID-19 vaccine at least 6 months after their Pfizer-BioNTech primary series, based on their individual benefits and risks, and
  • People aged 18-64 years who are at increased risk for COVID-19 exposure and transmission because of occupational or institutional setting may receive a booster shot of Pfizer-BioNTech’s COVID-19 vaccine at least 6 months after their Pfizer-BioNTech primary series, based on their individual benefits and risks.

Learn more from the CDC

What’s the difference between a booster dose and an additional dose?

Sometimes people who are moderately to severely immunocompromised do not build enough protection when they first get a vaccination. When this happens, getting an additional dose of the vaccine can sometimes help them build more protection against the disease. This appears to be the case for some immunocompromised people and COVID-19 vaccines.

In contrast, a “booster dose” refers to another dose of a vaccine that is given to someone who built enough protection after vaccination, but then that protection decreased over time (this is called waning immunity).

Can individuals who have received the Moderna or Johnson & Johnson (Janssen) vaccines receive a booster?

At this time, Pfizer-BioNTech is the only COVID-19 vaccine authorized for boosters. The CDC is evaluating available data in the coming weeks to swiftly make additional recommendations for other people who got the Moderna or Johnson & Johnson vaccines.

How can I get a COVID-19 booster through UI Health Care?

Eligible individuals can schedule their COVID-19 booster in MyChart or online.

How do I check when I received my last dose of the COVID-19 vaccine?

You can view the date of your last COVID-19 vaccination on your COVID-19 vaccine card, which should also list the type of vaccine you received (Pfizer-BioNTech, Moderna, or Johnson & Johnson).

If you received your initial dose(s) of the COVID-19 vaccine through UI Health Care and have a MyChart account, you can find your vaccination information in the COVID-19 menu item under the “My Record” heading.

Can I mix and match vaccines? For example, if I received Moderna for my first two doses, can I receive a booster of the Pfizer-BioNTech vaccine?

No. The CDC recommends that the booster dose you receive is the same vaccine you originally received.

If I’m fully vaccinated against COVID-19, why do I need a booster dose?

The COVID-19 vaccines are working very well to prevent severe illness, hospitalization, and death. With the Delta variant’s dominance as the circulating strain and cases of COVID-19 increasing significantly across the United States, a booster dose will help strengthen protection against severe disease in those populations who are at high risk for exposure to COVID-19 or the complications from severe disease.

I am immunocompromised and received an additional dose of an mRNA vaccine. Am I eligible to receive a booster?

If you received an additional dose of the Moderna or Pfizer vaccine, you are not yet eligible to receive a COVID-19 booster but may be in the future.

Can I receive the booster vaccination at the same time as the flu vaccination?

Yes, these two vaccinations can be administered at the same time if offered at the same location, though it is recommended that you receive the vaccinations in separate limbs.

What can I expect from the booster vaccination?

The booster vaccination is the same as the original two doses of the Pfizer-BioNTech vaccine. You should expect to have a similar reaction to the first two doses.

What are the common side effects of the vaccine?

  • Arm pain
  • Headache
  • Fatigue
  • Fever
  • Chills

When am I considered fully vaccinated?

If you are not immunocompromised, you are considered fully vaccinated two weeks after completing a two dose mRNA vaccine series (like the Pfizer-BioNTech or Moderna vaccines), or the one dose Johnson & Johnson (Janssen) vaccine.

If you are immunocompromised, you are considered fully vaccinated two weeks after completing the two dose mRNA vaccine series (like the Pfizer-BioNTech or Moderna vaccines) plus the additional vaccine dose. You are considered fully vaccinated two weeks after receiving the one dose Johnson & Johnson (Janssen) vaccine.

I've already had my COVID-19 vaccine. What happens if I don’t get a booster dose?

The COVID-19 vaccines are working very well to prevent severe illness, hospitalization, and death. With the Delta variant’s dominance as the circulating strain and cases of COVID-19 increasing significantly across the United States, a booster dose will help strengthen protection against severe disease in those populations who are at high-risk for exposure to COVID-19 or the complications from severe disease.

If I've already had COVID-19, do I still need to get a booster dose?

Yes. In people who contract the virus, COVID-19 can cause mild to severe symptoms, with varying levels of immune system response to the virus. It’s not guaranteed that your immune response from a COVID-19 infection will be protective against a new infection.

Should I still get my COVID-19 booster vaccine if I have had a monoclonal antibody treatment for COVID-19?

If you have received a monoclonal antibody treatment for COVID-19, you should wait 90 days before getting your COVID-19 booster vaccine. As a reminder, the booster dose must be at least 6 months after your second dose of the COVID-19 vaccine. You do not need to defer your flu vaccine.

Last reviewed: 
October 2021

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