The CDC has clarified who is considered immunocompromised enough to receive the third dose of mRNA vaccines.
The ACIP of the CDC and the FDA have agreed on appending the Emergency Use Authorization for the mRNA vaccines in individuals who are moderately to severely immunocompromised to receive a third dose booster. 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