All COVID-19 vaccines available in the United States are effective at preventing COVID-19, especially severe disease, hospitalization and death. Getting a COVID-19 vaccine gives most people a high level of protection against COVID-19, even against new variants.
Pfizer-BioNTech and Moderna have each created an updated booster dose formula designed to protect against original strains of the virus, as well as Omicron variants that cause most new infections. The CDC recommends people 6 months 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 two formulas that boost immunity against the original coronavirus strain and also protect against newer Omicron variants. Note that for children age 6 months to 4 years who get the Pfizer primary series, the updated bivalent vaccine will be used as the third dose in the series, rather than as a separate booster.
The best way to slow the emergence of new variants is to reduce the spread of infection by taking measures to protect yourself, including getting a COVID-19 vaccine when available. For more information on COVID-19 variants, please visit https://www.cdc.gov/coronavirus/2019-ncov/transmission/variant.html.