On August 13, 2021, the Centers for Disease Control and Prevention recommended that moderately to severely immunocompromised people receive a third dose of the Pfizer-BioNTech or Moderna mRNA COVID-19 vaccines at least 28 days after their second dose. The same mRNA vaccine administered for the first and second doses should be used for the third dose.
Per CDC guidance, individuals who should receive a third dose include those who have:
Active cancer treatment for solid tumors or cancers of the blood
Received a solid 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
Individuals should talk to their healthcare provider about their medical condition, and whether getting an additional dose is appropriate for them. Although hospitalizations and fatalities among fully vaccinated individuals are rare, data from the CDC suggests that immunocompromised individuals may have a reduced response to the COVID-19 vaccination, leaving them more susceptible to illness.
At this time, the CDC’s recommendation does not apply to the Johnson & Johnson/Janssen COVID-19 vaccine, as there is not enough data to determine whether immunocompromised people who received the J&J vaccine have an improved antibody response following an additional dose of the same vaccine.
Third dose mRNA boosters for all other individuals are currently under review by the CDC, FDA and ACIP.