*Any COVID-19 vaccine can be used for the booster dose in people ages 18 years and older, though mRNA vaccines are preferred. For people ages 12–17 years, only Pfizer-BioNTech can be used. People ages 5–11 years should not receive a booster dose.
†Only Pfizer-BioNTech or Moderna COVID-19 Vaccine should be used
Primary series for people with moderate or severe immunocompromise
mRNA COVID-19 vaccines
A 3-dose primary series is recommended for people ages 5 years and older who are moderately or severely immunocompromised at the time of vaccination (Table 3). The same mRNA vaccine product should be used for all doses of the primary series (see Interchangeability of COVID-19 vaccine products).
Pfizer-BioNTech COVID-19 Vaccine (5 years and older): The second dose is administered 3 weeks after the first dose; the third dose is administered at least 4 weeks after the second dose.
Moderna COVID-19 Vaccine (18 years and older): The second dose is administered 4 weeks after the first dose; the third dose is administered at least 4 weeks after the second dose. The dose is 100 mcg (0.5 ml) for all doses in the primary series.
Janssen COVID-19 Vaccine
A primary Janssen vaccine dose is recommended for people ages 18 years and older who are moderately or severely immunocompromised, followed by a second (additional) dose using an mRNA COVID-19 vaccine at least 4 weeks later (see Appendix B for additional information). If Moderna COVID-19 vaccine is used for the second dose, administer a 100 mcg (0.5 ml) dose.
Booster doses for people with moderate or severe immunocompromise
Booster doses are recommended for people 12 years of age and older after completion of primary vaccination.
mRNA COVID-19 vaccine primary series
A single booster dose is recommended at least 3 months after the third dose in the primary series, for a total of four doses, preferably with an mRNA COVID-19 vaccine. If Moderna vaccine is used for the booster dose, a 50 mcg (0.25 mL) dose should be used.
Janssen COVID-19 primary vaccination
A single booster dose is recommended at least 2 months after the 2nd (additional) dose, for a total of 3 doses (1 Janssen vaccine dose followed by 1 additional mRNA vaccine dose, then 1 booster dose). mRNA vaccines are preferred for the booster dose. If the Moderna vaccine is used for the booster dose, a 50 mcg (0.25 ml) dose should be used.
Special situation: Many recipients of Janssen COVID-19 Vaccine may have already received a booster dose (Pfizer-BioNTech, Moderna [50 mcg, 0.25 ml], or Janssen vaccine), without having had the 2nd (additional) mRNA vaccine dose. In this situation, regardless of type and timing of vaccine received as the 2nd dose, administer a Pfizer-BioNTech vaccine or a Moderna vaccine (100 mcg [0.5 mL]) as the 3rd dose at least 2 months after dose 2. See Appendix B for additional dose information for Janssen COVID-19 Vaccine recipients.
Table 3: COVID-19 vaccination schedule for people with moderate or severe immunocompromise*
Number of primary vaccine doses
number of boster doses
Interval between 1st an 2nd dose
Interval between 2nd an 3rd dose
Interval between 3rd and 4th dose
1 Janssen, followed by 1 mRNA
Description of moderate and severe immunocompromising conditions and treatment
Moderate and severe immunocompromising 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 chimeric antigen receptor (CAR)-T-cell therapy or hematopoietic cell transplant (HCT) (within 2 years of transplantation or taking immunosuppression therapy)
Moderate or severe primary immunodeficiency (e.g., DiGeorge syndrome, Wiskott-Aldrich syndrome)
Advanced or untreated HIV infection (people with HIV and CD4 cell counts <200/mm3, history of an AIDS-defining illness without immune reconstitution, or clinical manifestations of symptomatic HIV)
Active treatment with high-dose corticosteroids (i.e., ≥20 mg prednisone or equivalent per day when administered for ≥2 weeks), 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
Factors to consider in assessing the general level of immune competence in a patient include disease severity, duration, clinical stability, complications, comorbidities, and any potentially immune-suppressing treatment. Age or place of residence alone (e.g., residence in a long-term care setting), independent of a patient’s medical condition, should not be used to determine the level of immune competence, as the balance of benefits and risks of a third primary dose for people who are not moderately or severely immunocompromised is currently unknown.