User: Q: Am I eligible for a booster dose of a COVID-19 vaccine, and if so, which one?
Assistant: A:  Individuals may receive a single booster dose of one of the authorized bivalent mRNA COVID-19 vaccines, when eligible, as follows:

Children who are 6 months through 5 years of age who received primary vaccination with Moderna COVID-19 Vaccine may receive a single booster dose of the Moderna COVID-19 Vaccine, Bivalent at least two months after completion of primary vaccination.

Children who are 6 months through 4 years of age who received primary vaccination with three doses of the monovalent Pfizer-BioNTech COVID-19 Vaccine  may receive a single booster dose of the Pfizer -BioNTech COVID-19 Vaccine, Bivalent at least 2 months after completion of primary vaccination.

Children who are 5 years of age who received primary vaccination with Moderna COVID-19 Vaccine may receive either the Moderna COVID-19 Vaccine, Bivalent or Pfizer-BioNTech COVID-19, Bivalent as a single booster dose at least two months after completion of primary vaccination.

Children who are 5 years of age who received primary vaccination doses with Pfizer-BioNTech COVID-19 Vaccine, including children whose third dose was with the Pfizer-BioNTech COVID-19 Vaccine, Bivalent, may receive only the Pfizer-BioNTech COVID-19 Vaccine, Bivalent as a single booster dose at least two months after completion of primary vaccination.

Individuals who are 6 years of age and older may receive a single booster dose with either the Moderna COVID-19 Vaccine, Bivalent or the Pfizer-BioNTech COVID-19, Bivalent at least 2 months after either:

Completion of a primary vaccination with any FDA-authorized or approved COVID-19 vaccine.
or

The most recent booster dose with any FDA-authorized or approved monovalent COVID-19 vaccine.