COVID-19 Booster Shots & Additional Doses

In January 2022, the CDC approved the indications: boosters for ages 12 years and older 5 months or more after their second dose, and a third dose of either Pfizer-BioNTech or Moderna COVID-19 vaccines 28 days after their second dose for ages 5 years and older who are immunocompromised.

The CDC also said eligible adults could “mix and match” and choose to receive a different booster vaccine from the one(s) initially received. The Moderna COVID-19 single booster dose is half of the dose that is administered for a primary series dose.

One should get a booster if you are:

  • Ages 12 years and older and received both doses or 3 doses (if immunocompromised) of Pfizer-BioNTech at least 5 months ago.
  • Ages 18 years and older and received both doses or 3 doses (if immunocompromised) of Moderna COVID-19 vaccine at least 5 months ago.
  • Ages 18 years and older and had the Janssen/Johnson & Johnson vaccine at least 2 months ago.

Difference between an additional dose and a booster shot

  • An additional dose is for people who may not have had a strong enough immune response from the first two doses.
  • A booster shot is for people whose immune response may have weakened over time.

Who can get an additional vaccine dose?

Immunocompromised individuals include the following:

  • Recent or current treatment of a solid tumor or hematologic malignancy
  • Solid-organ, chimeric antigen receptor (CAR-T), or stem cell transplant within the last two years
  • Moderate to severe primary immunodeficiency (PID)
  • Advanced or untreated HIV
  • Active treatment with high-dose corticosteroids (i.e., ≥20 mg prednisone or equivalent per day), alkylating agents, antimetabolites, transplant-related immunosuppressive drugs, cancer chemotherapeutic agents classified as severely immunosuppressive, tumor necrosis factor (TNF) blockers, and other biologic agents that are immunosuppressive or immunomodulatory
  • Based on clinician assessment of need, chronic medical conditions associated with immunosuppression (e.g., asplenia, chronic renal disease)

The additional dose of an mRNA COVID-19 vaccine should be administered at least four weeks (28 days) after the second dose of the Pfizer-BioNTech COVID-19 vaccine or Moderna COVID-19 vaccine.

Patients should try to match the vaccine with the primary series, but the other mRNA COVID-19 vaccine product may be administered if that is not possible.

Antibody testing and T cell testing are not recommended to evaluate the need for an additional dose of the vaccine because the utility of such testing is not known.

Find a COVID-19 Vaccine: Click for information on how to get a COVID-19 vaccine.  For King County residents, click for a list of pop-up clinics.  Click for additional resources to get a booster in Western WA.