The CDC recommends the Moderna, Novavax and Pfizer-BioNTech COVID-19 vaccines for the primary vaccination series. Clinical trials and observational studies show that all COVID-19 vaccines authorized in the United States are effective at preventing COVID-19, especially severe disease, hospitalization, and death.
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. 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 monovalent Novavax booster and the Johnson & Johnson primary and booster vaccinations are authorized for people 18 and older in limited situations.
The recommended vaccination schedule from the Centers for Disease Control and Prevention, including dosage, is available here.