Why Should Immunocompromised People Get A Third COVID-19 Vaccine Dose?


The Centers for Disease Control and Prevention (CDC) and the Advisory Committee of Immunization Practices (ACIP) recently recommended that those who are immunocompromised receive a third dose of a Pfizer or Moderna vaccine. Getting a third dose will boost your protection against COVID-19, which is especially important for those with weakened immune systems.

“Studies suggest that fully vaccinated immunocompromised people make up 40 to 44% of hospitalized COVID-19 cases,” says Dennis Cunningham, M.D., medical director of infection control and prevention at Henry Ford Health System. “If you are immunocompromised, you cannot fight infections and diseases as well as other people. And it limits your body’s ability to produce protective antibodies after being vaccinated. A third vaccine dose will give you additional antibody protection from the virus.”

Here, Dr. Cunningham answers questions about third doses in immunocompromised people.

Q: Is it safe to get a third shot?

A: The safety profile is the same as for the first and second vaccine doses. Studies with immunocompromised people did not show severe adverse effects after a third dose. The effectiveness of additional COVID-19 vaccine doses in immunocompromised people is very good. After receiving the third shot, many people developed protective antibodies.

The Food and Drug Administration (FDA) has updated the Emergency Use Authorization (EUA) for the Moderna and Pfizer vaccines to authorize a third vaccine dose for immunocompromised people.

Q: Is the third shot different from the original two shots?

A: No. The third shot contains the same ingredients and the same amount of vaccine as the first and second shots.

Q: Will side effects be worse after the third shot?

A: Side effects after a third shot of Moderna or Pfizer are similar to what people experience after receiving the first two shots. Most symptoms are mild to moderate, and the most common side effects are fatigue and injection-site pain.

Q: Will the third shot improve my protection against the Delta variant?

A: Yes, it will improve your protection against all strains of the COVID-19 virus, including the Delta variant. It will also reduce the chances of getting very sick, if you do contract COVID-19.

Q: When should I get my third shot?

A: You should get your third shot at least 28 days after receiving your second shot of Moderna or Pfizer.

Q: Which vaccine should I receive for my third shot?

A: If you received Moderna for your first two shots, you will receive Moderna for your third shot. If you received Pfizer for your first two shots, you will receive Pfizer for your third shot.

If you received Johnson & Johnson for your first shot, an additional shot of the Johnson & Johnson vaccine has not been approved. We don’t know yet if a second shot of the Johnson & Johnson vaccine will result in an improved immune response for immunocompromised people. Research is ongoing.

Q: How do I know if I’m immunocompromised?

A: You are considered immunocompromised if you:

  • Have been receiving active cancer treatment for tumors or cancers of the blood.
  • Received an organ transplant.
  • Received a stem cell transplant.
  • Have primary immunodeficiency (such as DiGeorge syndrome, Wiskott-Aldrich syndrome, Bruton’s agammaglobulinemia, or severe combined immunodeficiency).
  • Have advanced or untreated HIV infection (CD4 count < 200).
  • Are being treated with high-dose corticosteroids or other drugs that may suppress your immune response.

If you are unsure whether you are considered immunocompromised, please contact your doctor.

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If you are immunocompromised, we encourage you to get your third shot wherever you can, such as CVS, Walgreens, Kroger and Meijer. Get answers to your vaccine FAQs now. 

Dr. Dennis Cunningham is the medical director of infection control and prevention at Henry Ford Health System.  

Categories: FeelWell