The Food and Drug Administation authorized reformulated versions of the Moderna and Pfizer-BioNTech vaccines that aim to protect against the omicron variant.

The new shots target both the original strain of the coronavirus and the omicron BA.4/BA.5 subvariants that most people are catching now. This double-barreled vaccine is called a bivalent vaccine.

"The FDA has been planning for the possibility that the composition of the COVID-19 vaccines would need to be modified to address circulating variants. ... We have worked closely with the vaccine manufacturers to ensure the development of these updated boosters was done safely and efficiently," said Dr. Peter Marks, director of the FDA's Center for Biologics Evaluation and Research, in an agency statement. "The FDA has extensive experience with strain changes for annual influenza vaccines. We are confident in the evidence supporting these authorizations."

The Moderna COVID-19 vaccine is authorized for use as a single booster dose in people 18 and older. The Pfizer-BioNTech booster is authorized for people 12 years and up. People are eligible for the new boosters two months after completing their initial vaccination or their last booster shot.

The federal government plans to make the boosters available starting next week. In advance of the FDA's decision, Dr. Ashish Jha, the White House COVID-19 Response Coordinator told NPR that the new boosters represented "a really important moment in this pandemic."

Public health officials hope they will help contain a possible fall and winter surge.

But there is also skepticism about how big a difference the boosters can make. "It could be problematic if the public thinks that the new bivalent boosters are a super-strong shield against infection, and hence increased their behavioral risk and exposed themselves to more virus," John Moore, an immunologist at Weill Cornell Medicine in New York, told NPR before the FDA decision.