The CDC recommends people 5 and older receive an age-appropriate, updated mRNA booster dose if at least 2 months have passed since their primary series or since their most recent booster dose. Updated boosters of Pfizer-BioNTech and Moderna contain a bivalent formula that both boosts immunity against the original coronavirus strain and also protects against the newer Omicron variants that now cause most cases. Updated boosters are expected to provide better protection against the virus and address waning vaccine effectiveness over time. A person can receive a booster of a COVID-19 vaccine that is different than the COVID-19 vaccine they received for their primary series.
Booster shots are not available for children under 5. The monovalent Novavax booster and the Johnson & Johnson primary and booster vaccinations are authorized for people 18 and older in limited situations. See additional recommendations for people who are moderately to severely immunocompromised.