New versions of the Pfizer-BioNTech and Moderna COVID-19 vaccine booster shots, have been authorized by the US Food and Drug Administration (FDA) on Wednsday.

The boosters will protect against the coronavirus strains circulating most widely in the US, including the highly contagious BA.4 and BA.5 omicron subvariants.

“The public can be assured that a great deal of care has been taken by the FDA to ensure that these bivalent Covid-19 vaccines meet our rigorous safety, effectiveness and manufacturing quality standards for emergency use authorization,” said Dr. Peter Marks, the agency’s top vaccine regulator, in a statement.

The FDA authorized Pfizer’s modified booster for people ages 12 and older.

The Moderna booster was authorized for those 18 and up.

Patients who have received the two-dose primary series of either vaccine, or those who have gotten the initial two doses plus one or two boosters, are eligible for the updated booster shots, according to the FDA, as long as two months have passed since their last shot.

“In terms of trying to stave off serious outcomes and symptomatic disease, one needs to refresh the immune system with what is actually circulating,” said Marks. “We believe the benefits of receiving a boost now at least two months after are going to outweigh the risks.”

The US government agreed to buy 105 million doses of the Pfizer vaccine and 66 million doses of Moderna.

Even with the FDA’s announcement, the boosters still have one last hurdle to clear before making their way to the public.

The Centers for Disease Control and Prevention (CDC) still needs to issue its recommendation on how the shots should be used. The agency’s Advisory Committee on Immunization Practices is scheduled to vote Thursday. If approved, the vaccinations could begin rolling out across the US starting next week.

“As we head into fall and begin to spend more time indoors, we strongly encourage anyone who is eligible to consider receiving a booster dose with a bivalent COVID-19 vaccine to provide better protection against currently circulating variants,” said FDA Commissioner Robert M. Califf in a statement.