The US Food and Drug Administration on Wednesday authorized the retooled COVID-19 booster shots of both Moderna and Pfizer/BioNTech that target the currently dominant BA.4/BA.5 Omicron subvariants of the coronavirus.
Both vaccines include the original version of the virus targeted by all the previous COVID shots as the country prepares for another vaccination campaign in the fall season.
The FDA authorized Moderna's MRNA.O vaccine for those aged 18 and above and Pfizer's for those aged 12 and above to be given at least two months after the primary vaccination series or the most recent booster shot.
The US government has secured 105 million doses of Pfizer's updated shots and 66 million doses of Moderna's bivalent vaccine to stave off the worst effects of a likely surge in infections as schools reconvene and people spend more time indoors as the weather grows colder.
Pfizer said it has some doses ready to ship immediately and can deliver up to 15 million doses by September 9.
The FDA in June asked vaccine makers to tailor shots to the two subvariants responsible for the most recent surge in infections worldwide. The BA.5 subvariant accounts for more than 88% of US infections.
Testing of updated COVID-19 booster shots incomplete
The vaccine makers have not completed testing of the updated BA.4/BA.5-based boosters in humans. The FDA is basing its decision on safety and effectiveness data from the original shots as well as from clinical trials conducted on bivalent boosters using the BA.1 Omicron subvariant.
"We are confident in the evidence supporting these authorizations," said Dr. Peter Marks, a senior official overseeing vaccines at the US FDA.
The USA Centers for Disease Control and Prevention's vaccine advisory panel is scheduled to meet on Thursday to make recommendations for use of the redesigned shots that Director Rochelle Walensky will take into consideration before making a final decision.