The CDC has approved mix and match booster doses for those who are eligible for a booster. This means that 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 or initial booster.
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. 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.
The recommended vaccination schedule from the Centers for Disease Control and Prevention is available here.