Public health officials may want to “boost people intermittently” with vaccines for the Chinese coronavirus, Dr. Anthony Fauci told Face the Nation’s Margaret Brennan on Sunday.

Brennan asked Fauci if people will need to be boosted “every six to eight months,” and he left the door wide open to that possibility.

“And that’s what we don’t know,” Fauci said, explaining it could be “conceivable” that a booster shot will provide a mild form of protection and “make the durability go well beyond six months and even longer.”

“Or it may be that we will have to boost people intermittently the way we do it with influenza,” he said, emphasizing that they “do not know definitively what that course is going to be. ”

“Whether it’s going to be a three shot and you’re done or three shots and then every once in a while you have to reboost. We’ll have to see how things roll out. Otherwise, we just can’t say something and guess about it,” he said.

Those remarks highlight concerns from critics, such as Florida Gov. Ron DeSantis (R), who have cautioned that public health officials will continue to move the goalposts in their effort to mandate the shot. Mere days ago, Fauci affirmed those suspicions, admitting that officials are evaluating changing the definition of fully vaccinated to apply only to those who also received a booster shot.

Governor Ron DeSantis (Gage Skidmore/Flickr)

When asked about breakthrough infections — infections contracted by people who have been vaccinated — Fauci said officials “really need to find out when you do boost an individual, how long does that immunity last, both from a laboratory standpoint and from a protection standpoint.”

“So the one thing we want to make sure, now that we’re getting full blown into the booster phase, we’ve got to make sure we know what that means from a clinical standpoint,” he said as Brennan pressed the White House medical adviser on why the Centers for Disease Control and Prevention (CDC) is seemingly not tracking breakthrough infections.

Fauci simply said it is a “very complicated situation” and suggested that the general public “doesn’t hear yet in time things that are being collected.”

“So there’s a lot of data, clearly a lot of data, that’s being collected by the CDC that people don’t know about yet,” he said, failing to sufficiently explain why comprehensive data on breakthrough infections is not easily accessible.

During the interview, Fauci added that the U.S. “certainly” has the potential to go into a fifth wave of the virus but said it will “be dependent upon what we do in the next few weeks to a couple of months,” pointing directly to vaccinations, despite the emergence of breakthrough infections:

For example, we have now about 62 million people in the country who are eligible to be vaccinated, who have not yet gotten vaccinated. Superimpose upon that, the fact that, unquestionably, the people who got vaccinated six, seven, eight, nine, 10 months ago, we’re starting to see an understandable diminution in the level of immunity.

However, given the waning of immunity, right now boosters are going to be very important. A third shot for those who got the two mRNAs and another additional shot for those who got the J&J. If we have a combination of getting as many people as we can get vaccinated as possible who have not yet gotten vaccinated, add on to it the children who are now eligible, the five to 11, there’s twenty eight million of those, and getting the many, many people now, 70% of the entire population of adults has been vaccinated- about 80% has been vaccinated.

“If we do that successfully in a very intensive way, we can mitigate any increase,” he added.

According to the CDC, 62.8 percent of Americans five and older are considered fully vaccinated.