Some Americans May Be Able to Get 4 Doses of COVID-19 Vaccine: FDA

Vials of Moderna's COVID-19 vaccine are seen in Bridgeport, Conn., in a file photograph. Joseph Prezioso/AFP via Getty Images

Some Americans may be able to get two additional doses of messenger RNA-based COVID-19 vaccines, with the possibility of the primary series being expanded from two to three doses, Food and Drug Administration (FDA) scientists said Thursday.

Moderna has sought authorization for a third dose, or a booster, for its COVID-19 vaccine and the FDA was discussing the emergency use application with its vaccine advisory panel.