Third dose of COVID-19 vaccine available to immunocompromised

The emergency use authorization for the Moderna and Pfizer COVID-19 vaccines has been updated to include a third dose for moderately or severely immunocompromised people 12 and older. Additional doses should be given a minimum of 28 days after completing a messenger RNA vaccination series. The Moderna and Pfizer COVID-19 vaccines are messenger RNA vaccines.

Immunosuppressed or immunocompromised refers to those who have medical conditions that compromise the immune system, such as advanced or untreated HIV, or patients who require treatment with immunosuppressant medications, such as chemotherapy. Immunosuppression lowers the effectiveness of COVID-19 vaccination. View the Centers for Disease Control and Prevention's list of conditions.

At this time, an additional dose is not recommended for those who received the Johnson & Johnson COVID-19 vaccine.

Mayo Clinic Health System is expected to start administering additional doses of COVID-19 vaccine to eligible patients as early as Tuesday, Aug. 17.

Patients eligible for additional COVID-19 vaccine doses across Mayo Clinic have been identified and will be contacted through Patient Online Services or by mail. They will be invited to schedule an appointment. Practice leaders also are discussing how additional doses can be made available to inpatients and those in transitional care units.

If you are eligible to receive a third dose of a COVID-19 vaccine because you are moderately or severely immunocompromised, you are encouraged to schedule an appointment as soon as you are invited to do so. If you are not a Mayo Clinic patient and believe you are eligible for an additional dose, you should seek an appointment at a local health care provider or pharmacy.

"The reason that immunocompromised people will need an additional vaccine is that their immune systems don't respond as well to the initial doses of the vaccine and the response they do have wears off over time," says Melanie Swift, M.D., co-chair of Mayo Clinic's COVID-19 Vaccine Allocation and Distribution Work Group. "People with a weakened immune system have a more difficult time fighting off infection than a healthy person."

The Mayo Clinic News Network team sat down with Dr. Swift as she answered questions about the additional dose of a COVID-19 vaccine:

Who can get an additional, or third, dose of a COVID-19 vaccine?

At this time, an additional, or third, dose of the Moderna or Pfizer COVID-19 vaccine is recommended to moderately or severely immunocompromised people 12 and older. People might be immunocompromised if they have advanced or untreated HIV, are undergoing chemotherapy to treat cancer or have had a solid organ transplant.

Will the third dose consist of one or two shots?

The third dose is a single dose of the Moderna or Pfizer COVID-19 vaccine.

If I qualify, do I have to wait a certain amount of time since I completed COVID-19 vaccination?

The authorizations for the messenger RNA vaccines have been amended to allow for a third dose to be administered at least 28 days following the two-dose regimen of the same vaccine or of another messenger RNA vaccine if the original is not available to people who have undergone solid organ transplantation or who are diagnosed with conditions that make them immunocompromised at an equivalent level.

Can health care providers who work with immunocompromised patients get a third dose of a COVID-19 vaccine?

Health care providers of immunocompromised patients are not eligible to receive a third COVID-19 vaccine dose.

Why is Mayo Clinic administering a third dose of COVID-19 vaccine if the World Health Organization asked for a pause on boosters?

Mayo Clinic supports the Advisory Committee on Immunization Practices and the Centers for Disease Control and Prevention's recommendations to administer a third dose of a COVID-19 vaccine to moderately or severely immunocompromised patients.

Does the third dose of COVID-19 vaccine need to be from the same company as a recipient's original COVID-19 vaccine?

The emergency use authorizations for the Moderna and Pfizer COVID-19 vaccines have been amended to allow for a third dose to be administered at least 28 days following the two-dose regimen of the same vaccine a person received. Another messenger RNA vaccine can be substituted if the original is not available, such as Moderna in place of Pfizer or vice versa.

Is there a difference between the third dose of a COVID-19 vaccine and the original two-dose vaccine series?

Technically, a third dose is being given for waning immunity after some period of time following completion of the original two-dose vaccine series. An additional dose of the Moderna or Pfizer COVID-19 vaccine is being recommended as an extension of the primary vaccination series for all patients who are moderately or severely immunocompromised, as they may not mount an adequate immune response to a two-dose vaccine series.

I received the J&J COVID-19 vaccine. Can I get an additional dose of a messenger RNA COVID-19 vaccine?

At this time, an additional dose of a messenger RNA COVID-19 vaccine is not recommended for those who received the J&J COVID-19 vaccine.

What should I do if I am immunocompromised and haven't been vaccinated for COVID-19?

If you haven't been vaccinated for COVID-19, you are encouraged to begin a vaccination series as soon as possible.

Information in this post was accurate at the time of its posting. Due to the fluid nature of the COVID-19 pandemic, scientific understanding, along with guidelines and recommendations, may have changed since the original publication date.