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Who Is Eligible for a COVID-19 Vaccine Booster Shot—and When?

Hands reaching for the COVID booster shot vial.

Ellen Lindner / Verywell

Key Takeaways

  • Booster shots are now approved for all three COVID-19 vaccines available in the U.S.
  • Individuals who meet eligibility criteria can choose any authorized booster shot.
  • Third doses of the COVID-19 mRNA vaccines are also authorized by the Food and Drug Administration (FDA) for some people who are immunocompromised.


COVID-19 vaccine booster shots are now available—though only to select people who are at increased risk. The U.S. Food and Drug Administration (FDA) expanded its emergency use authorization to include the Moderna and Johnson & Johnson COVID-19 booster vaccines for select populations.

The agency had previously authorized the Pfizer-BioNTech booster for certain individuals and a third dose of the COVID-19 mRNA vaccine for immunocompromised people who meet specific criteria.

Third Shots vs. Boosters

“Right now, the vaccines are still tremendously successful in preventing serious illness,” Aaron Eli Glatt, MD, FACP, FIDSA, FSHEA, the chair of medicine at Mount Sinai South Nassau in Oceanside, New York, and a spokesperson for the Infectious Disease Society, tells Verywell. 

Glatt says that because some immunocompromised people did not mount a good response to the vaccine, they need to get a third shot to ensure that they are protected.

For other fully vaccinated people, immunity wanes over time—which is why a booster shot dose might be beneficial. 

Third Shots for Immunocompromised People

After reviewing the available data, the FDA authorized the use of a third dose of the Pfizer-BioNTech and Moderna vaccines for immunocompromised people in mid-August.

“Those are people that never really mounted a good response,” says Glatt. “Studies show that if you give them an extra dose, [up to] 50% of them will mount a good response.”

Philip Felgner, PhD, the director of the Irvine Vaccine Research and Development Center at the University of California, Irvine, tells Verywell that immunocompromised people “are restricted from their movement around in the community when they’re concerned about being exposed to COVID in such a vulnerable position.”

The CDC’s Advisory Committee on Immunization Practices (ACIP) outlined the eligibility requirements for additional COVID vaccine doses.

A third dose is recommended for people in moderately to severely immunocompromised states either because of a medical condition or from taking immunosuppressive therapies, including: 

  • Active treatment for solid tumor and hematologic malignancies
  • Receipt of solid-organ transplant and taking immunosuppressive therapy
  • Receipt of chimeric antigen receptor (CAR)-T-cell or hematopoietic stem cell transplant (within 2 years of transplantation or taking immunosuppression therapy)
  • Moderate or severe primary immunodeficiency (e.g., DiGeorge syndrome, Wiskott-Aldrich syndrome)
  • Advanced or untreated HIV infection (people with HIV and CD4 cell counts <200/mm3, history of an AIDS-defining illness without immune reconstitution, or clinical manifestations of symptomatic HIV)
  • Active treatment with high-dose corticosteroids (i.e., ≥20 mg prednisone or equivalent per day when administered for ≥2 weeks), alkylating agents, antimetabolites, transplant-related immunosuppressive drugs, cancer chemotherapeutic agents classified as severely immunosuppressive, tumor-necrosis (TNF) blockers, and other biologic agents that are immunosuppressive or immunomodulatory.

The CDC says that an individual patient’s clinical team is best positioned to determine whether a third dose is appropriate, as well as when it should be given (within the recommendation that a third shot is received at least 28 days after completing a previous two-dose series).

The CDC estimates that about 2.7% of U.S. adults are immunocompromised and are at a greater risk for developing a breakthrough COVID-19 infection despite being fully vaccinated.

About 44% of hospitalized breakthrough COVID-19 infections are in immunocompromised people.

Booster Shots for Other Fully Vaccinated People

In September, the FDA granted emergency use authorization for a booster dose of the Pfizer-BioNTech vaccine, but only for select vaccine recipients. On October 20, the FDA expanded its emergency use authorization to include the Moderna and Johnson & Johnson COVID-19 booster vaccines.

The CDC now recommends a single booster dose to be administered at least six months after completion of the primary Pfizer or Moderna series in those who are:

Those 18 years and older who received the Johnson & Johnson vaccine are eligible for a booster at least two months after getting the initial vaccination.

According to the CDC, eligible individuals are able to choose any authorized COVID-19 booster—regardless of the vaccine type that was used for the initial vaccination. The Pfizer and Johnson & Johnson booster shots will be administered with the same dosage as the initial vaccine, whereas Moderna’s will be a half dose (50 mg).

What This Means For You

You can get a Moderna, Pfizer, or Johnson & Johnson booster vaccine if you:

  • Completed the COVID-19 mRNA vaccination series at least six months ago AND are 65 or older or 18 and over with underlying medical conditions, or at high risk for occupational or institutional exposure.
  • Initially received a Johnson & Johnson vaccine at least two months ago and are 18 or older.

If you’re immunocompromised, talk to your doctor about getting a third dose now. Experts recommend checking in with your state’s health department to get the latest information on where and when boosters will become available.

The information in this article is current as of the date listed, which means newer information may be available when you read this. For the most recent updates on COVID-19, visit our coronavirus news page.

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7 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Food and Drug Administration. Coronavirus (COVID-19) update: FDA takes additional actions on the use of a booster dose for COVID-19 Vaccines. Published October 20, 2021.

  2. Centers for Disease Control and Prevention. COVID-19 vaccine booster shot. Updated September 30, 2021.

  3. Food and Drug Administration. Coronavirus (COVID-19) update: FDA authorizes additional vaccine dose for certain immunocompromised individuals. Published August 12, 2021.

  4. Centers for Disease Control and Prevention. Interim clinical considerations for use of COVID-19 vaccines currently approved or authorized in the United States. Updated September 27, 2021.

  5. Oliver S. Data and clinical considerations for additional doses in immunocompromised people. Presented at Advisory Committee on Immunization Practices meeting, July 22, 2021; Atlanta, GA.

  6. Food and Drug Administration. FDA authorizes booster dose of Pfizer BioNTech COVID-19 vaccine for certain populations. Published September 22, 2021.

  7. Centers for Disease Control and Prevention. Who is eligible for a COVID-19 vaccine booster shot? Updated October 22, 2021.