The Centers for Disease Control and Prevention has endorsed the first updated COVID-19 booster shots.

The decision came just hours after advisers to the CDC voted to recommend reformulated versions of the Moderna and Pfizer-BioNTech COVID-19 vaccines. The vote was 13 in favor and one no vote.

"The updated COVID-19 boosters are formulated to better protect against the most recently circulating COVID-19 variant," Walensky said in a written statement announcing the recommendation.

"If you are eligible, there is no bad time to get your COVID-19 booster and I strongly encourage you to receive it," Walensky said.

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

The CDC advisers recommended that anyone age 12 and older get the new Pfizer-BioNTech boosters as authorized by the Food and Drug Administration. The updated Moderna COVID-19 vaccine is authorized for anyone 18 and older.

In both cases people would have to wait two months after completing their initial vaccination or their last booster shot. But many vaccine experts say it would be better to wait at least four months since the last shot or COVID infection, or the boosters won't work as well.

This is the first time the FDA has authorized COVID vaccines without requiring they get tested in people. To keep up with the rapidly evolving virus, the FDA relied on how well the shots stimulated the immune systems of mice. They also looked at how well similar shots targeted at earlier variants worked on people.

The companies and federal officials say there's no question the shots are safe and they argue the evidence indicates the reformulated boosters will help reduce the chances people will catch the virus and spread it.

But some people wonder if it would be better to wait for the results from human studies that are already underway.

"It certainly looks very promising," said CDC advisor Dr. Pablo Sanchez from The Ohio State University at Thursday's hearing. "I understand the constant shift of these variants but studies with the BA.4 and BA.5 are ongoing in humans and I just wonder if it's a little premature," he said. Sanchez was the only adviser to vote no. "I voted no because I feel we really need the human data," he explained. "There's a lot of vaccine hesitancy already. We need human data."

But other advisers were more comfortable, pointing out that flu vaccines are updated every year without being tested in people.

"This is the future that we're heading for," says Dr. Jamie Loehr of Cayuga Family Medicine. "We're going to have more variants and we should be treating this like the flu, where we can use new strain variants every year." Loehr says he's comfortable recommending the updated boosters, "even if we don't have human data."

Committee chair, Dr. Grace Lee, professor of pediatric infectious diseases at Stanford Medicine recognized there is some uncertainty, "I want to acknowledge it," she said. "And I just want to say that despite that I think we hopefully made a huge impact in our ability to weather this pandemic together."

Between 400 and 500 people are still dying every day in the U.S. from COVID-19 and public health officials are worried another surge could hit this fall or winter. The administration hopes the reformulated boosters will help contain a surge and protect people from serious disease or death.

The federal government plans to make the boosters available quickly. 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."

Now the CDC has signed off, few shots could be available as early as Friday, with a wider rollout next week.