The FDA recently announced the expansion of the emergency use authorizations (EUAs) of both Pfizer/BioNTech’s and Moderna‘s bivalent original/Omicron BA.4/5 Covid-19 messenger RNA (mRNA) vaccines. The expanded EUAs state that these current bivalent vaccines are now to be used for all primary and booster doses administered to individuals ages six months of age and older. As a result, the EUAs of the original monovalent mRNA vaccines developed by Pfizer/BioNTech and Moderna for the prevention of Covid-19 have been revoked, meaning they are no longer authorised for use in the US.

This decision was made to simplify the national vaccination schedule, which became confusing for individuals, including healthcare practitioners after multiple bivalent mRNA vaccines and the original monovalent vaccines were authorised for use by both vaccine developers. This led to a period of time when six mRNA vaccines, three from Pfizer/BioNTech and three from Moderna, were available in the US market. The EUAs for the bivalent original/Omicron BA.1 vaccines by both companies were revoked by the FDA in August 2022, after the BA.5 strain became dominant in the US, leaving four mRNA Covid-19 vaccines authorised for use.