Immunocompromised people who require an initial series of 3 doses of mRNA COVID-19 vaccine or two doses of Novavax COVID-19 vaccine should receive the initial series using the same brand, unless it is not feasible. If the same brand (referred to as a homologous dose) cannot be used for all primary series doses (e.g., the brand is unavailable at the time of the vaccination visit, the previous brand is unknown, or the patient would not be vaccinated with the previous brand due to a contraindication or other reason), then administer another appropriate brand. CDC recommends homologous doses for all doses administered to children younger than age 5 years. If the immunocompromised recipient is age 5 years or older, once the initial series is complete, any appropriate brand may be used for subsequent doses. CDC provides additional information at: www.cdc.gov/vaccines/covid-19/clinical-considerations/interim-considerations-us.html#Interchangeability.