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 the Omicron variants that cause most new cases. 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 latest CDC recommendations on booster doses help to ensure more people across the U.S. are better protected against COVID-19. The best way to protect yourself from COVID-19 is to get vaccinated and boosted if eligible. Vaccination and boosting are particularly important for individuals more at risk for severe COVID-19, such as older people and those with underlying medical conditions.
The recommended vaccination schedule from the Centers for Disease Control and Prevention, including dosage, is available here.