• COVID-19 Booster Doses FAQs

    Updated March 31, 2022

    Below are answers to commonly asked questions about COVID-19 vaccine boosters. These points are based on information released by the CDC. The AAFP reviews and approves all CDC recommendations related to vaccines. 

    CDC Updates Booster Recommendations to Further Protection for Vulnerable Populations  

    On March 29, after an expedited FDA review of evidence, the CDC updated its recommendations to allow a second booster dose of mRNA COVID-19 vaccine in individuals age 50 years and older and in people with certain types of immunocompromising conditions. This is especially important as the Omicron BA.2 subvariant becomes the dominant strain in the U.S. These recommendations have been reviewed and approved by the AAFP.

    CDC Updates Recommendations for mRNA COVID-19 Vaccine Booster Doses 

    With the new EUA amendments, all individuals 18 and older should receive a single booster dose of either vaccine, even if it different from their primary series. Individuals 12-17 can also receive a booster dose following completion of a primary series with Pfizer-BioNTech vaccine. The timing for an mRNA booster has also changed to be given at least 5 months following the second dose of the Pfizer-BioNTech or Moderna vaccines. The CDC has detailed recommendations and clinical considerations to help individuals decide if they need a booster, which vaccine to choose, and whether a different vaccine is appropriate. 

    About the Boosters and Eligible Populations

    Who can get a COVID-19 vaccine booster? (as of 1/6/22)
    CDC is recommending that all individuals aged 12 and older should get a booster. Timing on when to get a booster depends on which vaccine you received as your primary series. People who got the Pfizer-BioNTech or Moderna vaccines should get a booster at least 5 months after completing the primary series. People who got the Janssen (J&J) vaccine should get a booster at least 2 months later. 

    Can I get a different vaccine booster dose than the vaccine I originally got?
    You can "mix and match" booster dose in eligible individuals following completion of primary vaccination with a different COVID-19 vaccine. However, use of an mRNA vaccine is preferred in most situations. Some individuals may choose to get a different vaccine for their booster based on local availability, or individual risks and benefits. 

    Booster Dose Basics

    What’s the difference between a booster shot and an additional dose?
    An “additional dose” refers to people who are moderately to severely immunocompromised receiving an additional dose of an mRNA COVID-19 vaccine (Pfizer-BioNTech or Moderna). This is because they may not have received adequate protection from their initial 2-dose vaccine series. The additional dose is considered to be part of their primary series.

    A “booster dose” is a supplemental vaccine dose given to people when the immune response to a primary vaccine series was adequate but is likely to have decreased over time. Booster doses are given for many vaccines to "boost" the immune response (e.g. tetanus or TDaP). Additionally, booster doses of the Moderna vaccine are half of the dose used in the primary series. Learn more

    If I need a booster dose, does that mean that the vaccine is not working?
    The COVID-19 vaccines are working very well to prevent severe illness, hospitalization, and death, even against new variants. However, with the Delta and Omicron variants, we have seen reduced protection against mild and moderate disease over time. A booster shot maximizes protection.

    Should I get a second booster dose if I'm eligible?
    Yes. The CDC recently updated its booster vaccine recommendations to ensure certain vulnerable populations have the best protection against COVID-19 illness. This only applies to the mRNA vaccines. Eligible groups include:

    • People ages 50 years and older who received an initial COVID-19 booster dose (regardless of which vaccine was used) at least 4 months ago; 
    • People ages 12 years and older who are moderately or severely immunocompromised who received an initial COVID-19 booster dose (regardless of which vaccine was used) at least 4 months ago; and
    • People ages 18 years and older who received both a primary dose and a booster dose of J&J/Janssen COVID-19 vaccine at least 4 months ago.  

    What are the risks to getting a booster shot?
    So far, reactions that were reported after getting the COVID-19 vaccine booster shot were similar, or lower, to that seen after the primary series. Fatigue and pain at the injection site were the most commonly side effects reported. Serious side effects were rare. Get more information on potential rare side effects including myocarditis, anaphylaxis, TTS, and Guillain-Barre Syndrome, see CDC clinical considerations: 

    Am I still considered “fully vaccinated” if I don’t get a booster shot? 
    Everyone is still considered fully vaccinated two weeks after their second dose in a 2-shot series, such as the Pfizer-BioNTech or Moderna vaccines, or two weeks after a single-dose vaccine, such as the J&J/Janssen vaccine. However, people are encouraged to stay up to date with their vaccines and receive a booster dose when eligible. 

    If I got an additional dose of the mRNA vaccines, do I need to get a booster dose too?
    Individuals who are moderately to severely immunosuppressed and received an additional dose may get a booster dose starting at 5 months at following the third dose of the mRNA vaccines. 

    If I got the Janssen (J&J) vaccine originally, should I get booster from a mRNA vaccine?
    Yes, after reviewing recent safety and effectiveness data, the CDC is now recommending the mRNA COVID-19 vaccines be used in most situations.  Review situations where the Janssen vaccine may be considered. 

    Should I get a booster shot if I am pregnant?
    Yes. Individuals who are pregnant are considered to have underlying conditions and are recommended to get a booster dose based on their individual risks and benefits. 

    How do I decide which vaccine to get as my booster?
    All three of the FDA-approved or FDA-authorized vaccine boosters doses led to a strong antibody response following priming with the three vaccines. Heterologous (mixing) boosters were observed to result in similar or higher antibody responses compared to homologous (matching) boosters. However, the mRNA vaccines are preferred in most situations. Individuals should discuss the risks of the different approved/authorized vaccines with their family physician. Individuals aged 12-17 can only receive a booster dose of the Pfizer-BioNTech vaccine. 

    Potential risks of an mRNA COVID-19 vaccine include anaphylaxis and myocarditis/pericarditis. However, it is unknown how often these may occur. The CDC has provided additional considerations for people with a history of myocarditis

    Potential risks of a Janssen COVID-19 booster include thrombosis with thrombocytopenia syndrome (TTS) and Guillain-Barré Syndrome (GBS). Based on real world data after the primary dose of the J&J vaccine, men aged 50-64 years are at the highest risk for GBS women aged 18-49 years are at the highest risk of TTS. These groups may consider use of an mRNA vaccine for their booster dose. People who developed TTS after their initial Janssen vaccine should not receive a Janssen booster dose. 

    Vaccine Finder

    How do I get booster shot?
    Booster doses are free to receive similarly to the first 2 doses. You can also find a vaccine provider by visiting vaccines.gov, or you can text your ZIP code to 438829, or call 1-800-232-0233. Be sure to bring your vaccination card with you so the booster dose and date can be added. If you have lost your vaccination card, contact the vaccine provider where you got your first 2 doses or contact your state health department.