The Centers for Disease Control (CDC) has approved additional doses of the COVID-19 vaccine for certain people who have already been fully vaccinated.

The mobile clinics sponsored by UM Baltimore Washington Medical Center are offering additional doses of COVID vaccine — either a third dose for immunocompromised people or a booster shot for eligible people.

If you are getting a booster or third dose at our mobile clinic, you must bring your COVID-19 vaccine card. Learn how to get a COVID vaccine card replacement.

Eligibility for Additional Doses

Eligibility for these additional doses varies, depending on the type of vaccine initially received and when it was received.


Regardless of the vaccine initially received, people age 18 and older may receive any of the three vaccines available in the United States (Pfizer, Moderna or Johnson & Johnson), Pfizer is the only booster authorized for people ages 12-17. 

Note: Not all vaccine types may be available at each clinic.

To schedule a different vaccine, please see these resources for scheduling a COVID vaccine at other locations in Maryland.

The CDC encourages fully vaccinated people people age 12 and older to get a booster shot. People who initially received:

  • Pfizer or Moderna should get a booster at least five months after the second dose of their initial vaccination
  • J&J vaccine should get a booster shot t least two months after their initial vaccination

For additional details on who may get a booster, visit the CDC’s website.

Third Dose for Immunocompromised People

This third dose is not the same as a booster shot. The CDC recommends that people age 5 and older who are moderately to severely immunocompromised receive a third dose of an mRNA COVID-19 vaccine at least 28 days after the second dose of either the Pfizer or Moderna vaccine.

For immunocompromised children ages 5-17, make and appointment at our UM BWMG Vaccination Clinic to receive a third dose.

Unlike with a booster, you should receive the same vaccine as your initial vaccination.

This additional dose of Pfizer or Moderna is only for people who are immunocompromised as outlined in the CDC's recommendations. This includes people 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 2 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.

Please talk to your doctor about whether this third dose is appropriate for you.

Find a Mobile Vaccine Clinic