Third Dose Recommended for Immunocompromised
Aug 18, 2021
Monique Binkley Smith
Black woman wearing scarf

The Centers for Disease Control and Prevention (CDC) recommends people with moderately to severely compromised immune systems get an additional dose of Pfizer or Moderna COVID-19 vaccine.

According to the CDC, an additional dose for this population is strongly recommended because studies indicate these people don’t always build the same level of immunity after vaccination the way non-immunocompromised people do. The third dose may help moderate to severely immunocompromised people develop additional protection against COVID-19.

Vitals staff interviewed Jeffrey Silvers, M.D., medical director of infectious diseases at Sutter Health, for his insights on the new CDC recommendation.

Jeffrey Silvers, M.D.

Jeffrey Silvers, M.D.

Vitals: Can you help clarify who is eligible to receive an additional dose of Pfizer or Moderna COVID-19 vaccine?

Dr. Silvers: According to the new CDC guidance, moderately to severely immunocompromised people are eligible to receive an additional dose at least 28 days or about a month after they received their second dose of Pfizer or Moderna.

The CDC’s recommendation applies to moderately to severely immunocompromised people 12 years and older for Pfizer-BioNTech and 18 years and older for Moderna-NIAID 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 two 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

Vitals: Why isn’t this considered a booster?

Dr. Silvers: It’s a bit of a technical answer. Boosters are vaccine doses given to people who generated a strong immune response from the original regimen, but had a waning of that immunity over time.

The latest recommendation from CDC is related to the fact that many people who are moderately to severely immunocompromised didn’t generate a strong immune response to their first two doses of the Pfizer or Moderna mRNA vaccines. This means an additional dose may be necessary to stimulate a more robust immune response and that’s what CDC is now recommending.

Vitals: If someone was moderately to severely immunocompromised when they received their first two doses are they eligible for an additional dose?

Dr. Silvers: Yes. For example, if someone was receiving chemotherapy when they got their first and second doses of COVID-19 Pfizer or Moderna, their immune system was likely moderate to severely compromised at the time and may not have mounted as robust an immune response as we would like to see. The CDC is now recommending these patients get an additional dose of the vaccine to help improve their immunity to the virus.

Vitals: What about moderately to severely immunocompromised people who got the Janssen/J&J vaccine? Are they eligible for an additional dose?

Dr. Silvers: The FDA amended its emergency use authorization (EUA) for the Pfizer and Moderna COVID-19 vaccines to allow for an additional, third dose. But the FDA has not yet amended the EUA for the Janssen/J&J vaccine because it isn’t yet known whether immunocompromised people who received it have an improved immune response following an additional dose of the same vaccine. More research is needed before the CDC will make a recommendation. At Sutter Health, we will continue to follow federal guidelines and recommendations.

Vitals: When will an additional dose or booster be made available for everyone?

Dr. Silvers: At this time, the CDC recommends an additional dose for only those patients who have compromised immune systems. Federal health officials determined that this group may benefit from a third dose of the Pfizer or Moderna vaccines.

The FDA and CDC have not yet approved a booster for the general public and this third dose recommendation is limited to those who are moderately to severely immunocompromised.

However, the important thing for people to keep in mind is that studies indicate that all three COVID-19 vaccines available in the U.S. (Pfizer, Moderna and Janssen/J&J) remain effective against current variants, including the delta variant, in preventing hospitalization and death for most people who are fully vaccinated. So if you are age 12 or older and you haven’t yet been vaccinated, please get vaccinated as soon as possible.

For More Information

For more information on the COVID-19 vaccines, answers to frequently asked questions and how to get vaccinated, visit this updated COVID-19 vaccine webpage.

Note: This content is not intended to be a substitute for professional medical advice, diagnosis or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website.


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