Ventura County Public Health

Additional mRNA Dose for Immunocompromised Persons


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This message is intended for all healthcare providers in the County of Ventura.
Please distribute as appropriate.

Key Messages

  • The CDC recommends an additional mRNA COVID-19 vaccine dose for moderately and severely immunocompromised people after an initial 2-dose primary mRNA vaccine series.
  • An additional vaccine dose is not currently recommended by the CDC for immunocompromised persons who received a single dose of the J&J vaccine. The FDA is still evaluating data on the effectiveness of this vaccine for immunocompromised individuals.
  • Other fully vaccinated persons are adequately protected and do not need an additional dose nor a booster dose of COVID-19 vaccine at this time.

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Additional Dose of mRNA Vaccine for Moderate and Severely Immunocompromised Persons.

A 2-dose series of Pfizer and Moderna vaccine works very well in the majority of individuals, but there is evidence that some people who are moderately to severely immunocompromised have a reduced immune response and may benefit from a third dose. The CDC’s Advisory Committee on Immunization Practices (ACIP) recommends that people who are moderately to severely immunocompromised receive an additional dose of mRNA COVID-19 vaccine at least four weeks after completing their initial series. This ACIP recommendation follows the FDA amendment to emergency use authorizations (EUAs) for both the Pfizer and Moderna vaccines to allow for the use of an additional vaccine dose for certain immunocompromised.

For public health purposes, the CDC states that immunocompromised persons are still considered fully vaccinated > 2 weeks after completing a primary vaccine series (i.e., 2-dose Pfizer or Moderna vaccine series or a single dose of the Janssen vaccine). However, an additional third dose should be considered for people with moderate to severe immune compromise due to a medical condition or receipt of immunosuppressive medications or treatments. These conditions and treatments include but are not limited to:

  • Active treatment for solid tumor and hematologic malignancies • Receipt of solid-organ transplant and taking immunosuppressive therapy
  • Receipt of CAR-T-cell or hematopoietic stem cell transplant (within 2 years of transplantation or taking immunosuppression therapy)
  • Moderate or severe primary immunodeficiency (e.g., DiGeorge syndrome, WiskottAldrich syndrome)
  • Advanced or untreated HIV infection
  • Active treatment with high-dose corticosteroids (i.e., ≥20mg prednisone or equivalent per day), alkylating agents, antimetabolites, transplant-related immunosuppressive drugs, cancer chemotherapeutic agents classified as severely immunosuppressive, tumor-necrosis (TNF) blockers, and other biologic agents that are immunosuppressive or immunomodulatory.

Additional information for providers regarding the level of immune suppression associated with a range of medical conditions and treatments can be found:

The CDC has updated COVID-19 vaccine clinical considerations to include a new section on the considerations for use of an additional mRNA COVID-19 vaccine dose for immunocompromised persons. Some key points include:

  • The currently FDA-authorized COVID-19 vaccines are not live vaccines and therefore can be safely administered to immunocompromised people.
  • The additional dose should be administered at least 28 days after the completion of the initial mRNA COVID-19 vaccine series.
  • Ideally individuals should be vaccinated with the same vaccine as they received during their first and second dose but if that is not possible receiving a third dose with another mRNA vaccine is also acceptable. • This additional dose recommendation is only for persons who are moderately or severely immunocompromised.

The CDC has also published a new page for consumers COVID-19 Vaccines for Moderately to Severely Immunocompromised People.

Qualified individuals can go to any vaccine site for their third dose. More information at