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

COVID-19 vaccine boosters are recommended for all eligible groups. 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).

Learn more about vaccine boosters

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

After your primary COVID-19 vaccination series, you may have already received a booster dose of an mRNA vaccine—like Pfizer-BioNTech or Moderna—or Johnson & Johnson (Janssen).

Additionally, the Food and Drug Administration (FDA) and Centers for Disease Control and Prevention (CDC) have authorized a second booster dose of these COVID-19 vaccines for adults ages 50 and older—and other select individuals—at least four months after receiving their first booster dose of any approved COVID-19 vaccine.

For a full breakdown of first and second boosters, review the following tables:

First Booster

If your primary vaccination series was:

Who should get a booster?

When should I get my first booster?

Which booster should I get?

Pfizer-BioNTech

Everyone 12 years or older

At least 5 months after completing your primary COVID-19 vaccination series

Pfizer-BioNTech or Moderna (mRNA COVID-19 vaccines) are preferred in most situations.

Individuals 12–17 years old may only get a Pfizer-BioNTech COVID-19 vaccine booster.

Moderna

Everyone 18 years or older

At least 5 months after completing your primary COVID-19 vaccination series

Pfizer-BioNTech or Moderna (mRNA COVID-19 vaccines) are preferred in most situations.

Johnson & Johnson (Janssen)

Everyone 18 years and older

At least 2 months after receiving your J&J/Janssen COVID-19 vaccination

Pfizer-BioNTech or Moderna (mRNA COVID-19 vaccines) are preferred in most situations.

Second Booster

If your primary vaccination series was:

Who can get a second booster?

When can I get my second booster?

Which second booster can I get?

Pfizer-BioNTech

Adults 50 and older

*Get details for immunocompromised individuals

At least 4 months after receiving your first booster dose of any approved COVID-19 vaccine

Pfizer-BioNTech or Moderna (mRNA COVID-19 vaccines) are preferred in most situations.

Moderna

Adults 50 and older

*Get details for immunocompromised individuals

At least 4 months after receiving your first booster dose of any approved COVID-19 vaccine

Pfizer-BioNTech or Moderna (mRNA COVID-19 vaccines) are preferred in most situations.

Johnson & Johnson (Janssen)

Adults 50 and older who received Johnson & Johnson (Janssen) as their primary series dose and Moderna or Pfizer-BioNTech as their first booster.

Individuals ages 18 to 49 who received Johnson & Johnson (Janssen) as both their primary series dose and first booster dose

At least 4 months after receiving your first booster dose of any approved COVID-19 vaccine

Pfizer-BioNTech or Moderna (mRNA COVID-19 vaccines) are preferred in most situations.

*For individuals who are considered moderately to severely immunocompromised:
  • People considered moderately to severely immunocompromised are limited to those who have:
    • Been receiving active cancer treatment for tumors, or cancers of the blood
    • Received an organ transplant and are taking medicine to suppress the immune system
    • Received a stem cell transplant within the last 2 years or are taking medicine to suppress the immune system
    • Moderate or severe primary immunodeficiency (such as DiGeorge syndrome, Wiskott-Aldrich syndrome)
    • Advanced or untreated HIV infection
    • Active treatment with high-dose corticosteroids or other drugs that may suppress your immune response

If you are uncertain if you are eligible to receive an additional COVID-19 vaccine dose based on these criteria, please contact your primary care provider.

Immunocompromised Individuals

If your primary vaccination series was:

Who can get boosters?

When should I get my first booster?

When can I get my second booster?

Which booster can I get (first and/or second booster)?

Pfizer-BioNTech

Immunocompromised individuals ages 12 and older

At least 3 months after completing your primary COVID-19 vaccination series  including the additional dose (total of three doses)

At least 4 months after receiving your first booster dose of any approved COVID-19 vaccine

Pfizer-BioNTech or Moderna (mRNA COVID-19 vaccines) are preferred in most situations.

Moderna

Immunocompromised individuals ages 18 and old

At least 3 months after completing your primary COVID-19 vaccination series, including the additional dose (total of three doses)

At least 4 months after receiving your first booster dose of any approved COVID-19 vaccine

Pfizer-BioNTech or Moderna (mRNA COVID-19 vaccines) are preferred in most situations.

Johnson & Johnson (Janssen)

Individuals ages 18 or older who received an additional dose of either the Pfizer-BioNTech or Moderna vaccine

At least 2 months after receiving your primary J&J/Janssen COVID-19 vaccination series, including the additional dose (total of two doses)

At least 4 months after receiving your first booster dose of any approved COVID-19 vaccine

Pfizer-BioNTech or Moderna (mRNA COVID-19 vaccines) are preferred in most situations.

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 [Janssen]).

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?

Yes, vaccines may be mixed and matched.

Your first booster does not need to match your primary vaccination series, nor does your second booster need to match your first booster. For example, you could have Johnson & Johnson as your primary vaccination series, Pfizer-BioNTech as your first booster, and Moderna as your second booster.

However, it is recommended that individuals receive the Pfizer-BioNTech or Moderna vaccines as a booster in most situations—regardless of the vaccine you received as part of your primary vaccination series.

If you have questions or concerns, please consult your primary care provider.

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. A booster dose will help strengthen protection against severe disease in those populations who are at high risk for exposure to COVID-19 or complications from severe disease.

Can I receive a 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 a booster vaccination?

You should expect to have a similar reaction to the first two doses, regardless of which initial vaccine you received or which booster vaccine you received.

The Pfizer-BioNTech booster vaccines are the same as the original two doses of the Pfizer-BioNTech vaccine (30 micrograms).

The two primary doses in the Moderna vaccine series are 100 micrograms each. Each booster dose is half of the original dosage of the first two vaccinations (50 micrograms).

What are the common side effects of the vaccine?

  • Arm pain
  • Headache
  • Fatigue
  • Fever
  • Chills

When am I considered fully vaccinated?

You are considered fully vaccinated two weeks after completing a two dose mRNA vaccine series (like the Pfizer-BioNTech or Moderna vaccines), or two weeks after 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. It’s not guaranteed that your immune response from a COVID-19 infection will be protective against a new infection. A booster dose will further help to protect you against COVID-19 and is recommended even if you have already contracted the virus.

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, a 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.

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 another 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 these cases, the additional dose is considered part of their original COVID-19 vaccination series. Certain immunocompromised individuals require three doses of the Pfizer-BioNTech or Moderna vaccines as their primary series instead of the two doses required by the general population. Similarly, certain immunocompromised individuals require two doses of the Johnson & Johnson (Janssen) vaccine as their primary series instead of the one dose required by the general population.

In contrast, a “booster dose” refers to another dose of a vaccine given to someone who built enough protection after their primary COVID-19 vaccination series (two doses of Pfizer-BioNTech/Moderna or one dose of Johnson & Johnson). Over time, immunity provided by the vaccines starts to decrease—something known as “waning immunity.” Booster doses are administered to re-strengthen immunity against the COVID-19 virus.

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

If you are age 18 or older and received an additional dose of the Moderna vaccine, or age 12 years or older and received an additional dose of the Pfizer-BioNTech COVID-19 vaccine, you are eligible for boosters.

For a full breakdown on first and second boosters, review "Who is eligible to receive a COVID-19 vaccine booster?" earlier on this page.

Last reviewed: 
April 2022

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