Immunocompromised covid vaccine booster
People with compromised immune systems who have already received two doses of either the Pfizer or Moderna COVID-19 vaccine are eligible for a third shot if they meet these immunocompromised conditions.

On August 12, 2021, the U.S. Food and Drug Administration (FDA) rolled out the emergency use authorizations (EUAs) for both the Pfizer-BioNTech COVID-19 vaccine and the Moderna COVID-19 vaccine in people with immunocompromised conditions. According to the Centers for Disease Control and Prevention (CDC), a booster dose of the COVID-19 vaccine is recommended for people who are moderate to severely immunocompromised, which includes people that:

  • Have been receiving active cancer treatment for tumors or cancers of the blood.
  • Are organ transplant recipients and are taking immunosuppressants (medications to suppress the immune system).
  • Have received a stem cell transplant within the last two years or are taking immunosuppressants.
  • Have moderate or severe primary immunodeficiency (a condition in which the immune system does not work correctly leading to frequent infections. Examples include DiGeorge syndrome, Wiskott-Aldrich syndrome, severe combined immunodeficiency or SCID).
  • Have advanced or untreated HIV infection.
  • Are receiving active treatment with high-dose corticosteroids or other drugs that may suppress the immune response.

If you are not sure whether you are eligible for an additional dose (booster shot) of the COVID-19 vaccine, you can discuss it with your doctor. For receiving a booster dose of the Moderna vaccine, the individual must be at least 18 years of age, whereas individuals who are 12 years and older are eligible to get the Pfizer-BioNTech COVID-19 vaccine.

Why is a COVID vaccine booster important for immunocompromised people?

Your immune system helps you fight infections and other diseases. Being immunocompromised means that you do not have an immune system strong enough to protect you from diseases. When an individual with a healthy immune system receives a vaccine, their immune system mounts a significant response against the antigen that helps them produce the antibodies to fight the infection against which the vaccine was given. In immunocompromised individuals, however, the immune system is unable to build an immune response to the vaccine as strong as individuals with a healthy immune system. Thus, they may need additional vaccine dosages (boosters) to boost their immune response.

About three percent of the adult population in the US is moderate to severely immunocompromised. These individuals are particularly vulnerable to the COVID-19 infection. When infected, they are also more likely to have severe complications. Studies have so far revealed that the efficacy of the COVID-19 vaccine may not be as good in immunocompromised individuals as in those with a healthy immune system.

Studies have also suggested that fully vaccinated immunocompromised individuals contribute to a large share of hospitalized vaccine breakthrough cases (cases in which people were infected by COVID-19 despite being fully vaccinated). Generally, vaccine breakthrough cases do not result in severe complications or hospitalization. However, in the case of immunocompromised individuals, there may be a higher chance of getting hospitalized.

Furthermore, a booster dose in immunocompromised individuals also reduces the risk of the spread of COVID-19 because these people tend to spread the virus more effectively (prolonged viral shedding) than those with a healthy immune system. Hence, a booster dose of the COVID-19 vaccine is beneficial for both the immunocompromised person and the community.

When should an immunocompromised individual get the COVID-19 vaccine booster dose?

According to the present guidelines, a booster dose of COVID-19 mRNA vaccine (Pfizer-BioNTech COVID-19 vaccine or Moderna COVID-19 vaccine) can be administered at least 28 days (four weeks) after the second dose of the same vaccine. This means if the person took two doses of the Pfizer-BioNTech COVID-19 vaccine, the booster must also be of that vaccine. Similarly, if the person took two doses of Moderna COVID-19 vaccine, the booster must also be that vaccine. If, however, the same mRNA vaccine product is not available or is unknown, the individual can be administered either of the mRNA COVID-19 vaccine (Pfizer-BioNTech COVID-19 or Moderna COVID-19).

How many booster shots of the COVID-19 vaccine can an immunocompromised person take?

The CDC presently recommends only one booster dose of the mRNA COVID-19 vaccine. This means that an individual should not take more than three doses of the mRNA COVID-19 vaccine in total.

Should immunocompromised individuals who received the J&J/Janssen COVID-19 vaccine also receive a booster dose?

No, the present guidelines do not recommend a booster dose for immunocompromised individuals who received the J&J/Janssen COVID-19 vaccine. This is because currently there is not enough data to support whether immunocompromised people who receive the J&J/Janssen COVID-19 vaccine will have a substantially improved immune response by receiving a booster dose of the same vaccine. Thus, the present emergency use authorizations (EUAs) by the FDA are only for the mRNA vaccines (Pfizer-BioNTech COVID-19 or Moderna COVID-19).

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Medically Reviewed on 8/18/2021
Centers for Disease Control and Prevention. COVID-19 Vaccines for Moderately to Severely Immunocompromised People.

U.S. Food and Drug Administration. Coronavirus (COVID-19) Update: FDA Authorizes Additional Vaccine Dose for Certain Immunocompromised Individuals.