NEWS

CDC Panel Recommends Third COVID-19 Vaccine Dose for Immunocompromised People

Nurse prepares a dose of the Pfizer COVID-19 vaccine

Mario Tama / Getty Images

Key Takeaways

  • A CDC advisory panel voted to recommend additional shots for immunocompromised individuals.
  • The recommendation applies to people with moderate to severe immunosuppression.
  • Studies show third doses are safe and effective for the mRNA vaccines by Moderna and Pfizer/BioNTech. Johnson & Johnson's vaccine is not authorized for use as a third dose among immunocompromised people, though it is authorized as a booster.

U.S. health officials voted August 13, 2021 to recommend an additional dose of COVID-19 vaccine for some immunocompromised people.

A panel of eight advisors to the Centers for Disease Control and Prevention (CDC) voted unanimously in favor of the recommendation.

Soon after, CDC Director Rochelle Walensky signed the recommendation, allowing millions of moderately and severely immunocompromised people to get a third shot of the Pfizer or Moderna vaccines. For individuals whose immune response was weak or non-existent after the initial doses, the additional shot may grant them a higher degree of protection against COVID-19.

“I want to be able to visit with vaccine friends and family, and not have to worry about becoming a breakthrough case,” a cancer survivor said during public comment.

The vote closely followed the Food and Drug Administration (FDA) authorization of a third dose of the COVID-19 vaccine for organ transplant recipients and individuals with similar levels of immunosuppression.

Who Will Qualify for a Third Dose?

The CDC recommendation applies to people who are moderately or severely immunocompromised.

These can include people who have the following medical conditions or receive the following treatments:

  • Active or recent treatment for solid tumor and hematologic malignancies.
  • Receipt of solid organ or recent hematopoietic stem cell transplants and taking immunosuppressive therapy. 
  • Receipt of CAR-T-cell or hematopoietic stem cell transplant (within two years of transplantation or taking immunosuppression therapy).  
  • Moderate or severe primary immunodeficiency (for example, DiGeorge, Wiskott-Aldrich syndromes).
  • Advanced or untreated HIV infection. 
  • Active treatment with high-dose corticosteroids (for example, greater than or equal to 20 milligrams of prednisone or equivalent per day), alkylating agents, antimetabolites, transplant-related immunosuppressive drugs, cancer chemotherapeutic agents classified as severely immunosuppressive, TNF blockers, and other biologic agents that are immunosuppressive or immunomodulatory.

What This Means For You

If you are moderately or severely immunocompromised, talk with your doctor to determine if and when you should receive a third dose of mRNA vaccine.

The CDC estimates that 2.7% U.S. adults, or about 7 million people, are immunocompromised. These individuals may receive a third shot 28 or more days after completing the two-dose mRNA series.

The recommendation applies to those 5 and older who got the Pfizer vaccine series and those 18 and older who got the Moderna vaccine series who are moderately or severely immunocompromised. People should try to get an additional dose that matches their earlier doses. If unavailable, mixing the mRNA vaccines is okay for those 18 and older, the panel said. Children and teens 5-17 years old can only receive the Pfizer vaccine at this time.

So far, there is insufficient data for the group to recommend that recipients of the Johnson & Johnson vaccine receive an additional—or third—dose (they can get a booster). The FDA said it is working to ensure that immunocompromised people vaccinated with the Johnson & Johnson vaccine become optimally protected.

Enhancing Protection for the Most Vulnerable

Immunocompromised individuals are more likely to get seriously ill from COVID-19 as they are less likely to produce protective antibodies after vaccination. For instance, organ transplant patients can have 0% to 79% immune response to the vaccines, the panel said, and around 40% of people hospitalized due to breakthrough infections are immunocompromised.

Among those with no detectable antibody response to initial schedule, one third to a half had some immunity after the third dose. But health experts are not entirely sure how a boost in antibodies will translate to COVID-19 prevention in this group.

The third doses appear to be “only moderately effective,” Peter Marks, MD, PhD, director of the FDA’s Center for Biologics Evaluation and Research said in the meeting. Since individuals will respond differently to the extra dosage, recipients should continue wearing masks, social distancing, and taking other safety precautions, he added.

The CDC is not recommending antibody tests before or after additional shots. Currently, there are no FDA-approved antibody tests to accurately measure post-vaccine immunity.

Clinicians who care for people with moderate and severe immunosuppression should consider their patients’ unique needs when recommending a third dose, according to Kathleen Dooling, MD, MPH, medical officer for the Division of Viral Diseases at the National Center for Immunization and Respiratory Diseases.

“This is a highly heterogeneous group with very complex medical needs that are going to vary by condition,” Dooling said. “Our attempt here was to make these clinical considerations a starting point, that will definitely need to be adapted by the clinical care team treating these individuals.”

Like the earlier shots, third doses will be free and administered at pharmacies and other health-care sites.

To minimize barriers, the panel said patients will not be required to present a letter from a doctor for the third shot. 

Boosters for the General Population

With COVID-19 cases, hospitalizations, and deaths on the rise in the U.S. due to the spread of the highly contagious Delta variant, other population groups are now eligible to receive a booster dose.

The FDA has now authorized a booster dose for all individuals 12 years and older in the U.S.

According to the CDC, you are eligible for a COVID-19 booster shot if:


  • You are 12 years of age and older and received the Pfizer primary vaccine series at least five months ago
  • You are 18 years of age and older and received the Moderna primary vaccine series at least five months ago
  • You are 18 years of age and older and received the Johnson & Johnson vaccine at least two months ago


Eligible adults are able to choose any authorized COVID-19 booster—regardless of the vaccine type used for the initial vaccination (although mRNA COVID-19 vaccines are preferred in most situations). Children and teens ages 12 to 17 who completed Pfizer's primary series are only eligible for the Pfizer booster.


The Pfizer and Johnson & Johnson boosters will be administered with the same dosage as the initial vaccine, whereas Moderna’s will be a half dose (50 micrograms).

The World Health Organization had called on wealthier countries to avoid administering booster shots until countries with lower vaccination rates have access to existing vaccines. France, Israel, the United Kingdom, and Germany have already announced they will dole out additional doses for immunocompromised individuals.

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.

3 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 multiple actions to expand use of Pfizer-BioNTech COVID-19 vaccine.

  2. Centers for Disease Control and Prevention. COVID-19 vaccine booster shots.

  3. Food and Drug Administration. Coronavirus (COVID-19) update: FDA takes additional actions on the use of a booster dose for COVID-19 vaccines.

By Claire Bugos
Claire Bugos is a health and science reporter and writer and a 2020 National Association of Science Writers travel fellow.