To be considered fully vaccinated, the Comirnaty (Pfizer) and Moderna vaccine require two doses, and the Johnson & Johnson (Janssen) vaccine requires one dose.

 A “booster dose” is another dose of a vaccine that is given to someone who built enough protection after vaccination, but then that protection decreased over time (this is called waning immunity). CDC has recommended Pfizer, Moderna, and Johnson & Johnson boosters for people 18 years and older who meet specific criteria.