In an interview with CBS' Face the Nation on Sunday, President Joe Biden's Chief Medical Adviser Dr. Anthony Fauci stressed the need for Food and Drug Administration approval of a vaccine before but gets used as a booster shot.

"I want to start with boosters, because we are just over two weeks away from September 20th. That is the date that the administration had planned to start administering vaccine boosters for adults. Is that still the plan?" Weijia Jiang asked.

"In some respects, it is. We were hoping that we would get the- both the candidates, both products, Moderna and Pfizer rolled out by the week of the 20th, said Fauci. "It is conceivable that we will only have one of them out, but the other will likely follow soon thereafter."

"And the reason for that is that we- as we've said right from the very beginning, we're not going to do anything unless it gets the- the appropriate FDA regulatory approval. And then the recommendation from the Advisory Committee on Immunization Practices," Fauci continued.

Fauci went on to say that while Pfizer has its data in and would most likely meet the deadline, Moderna has yet to. He hopes Moderna will be able to be approved by the 20th so that the rollout could be simultaneous, "but if not, we'll do it sequentially. So the bottom line is very likely, at least part of the plan will be implemented, but ultimately the entire plan will be."

In mid-August, President Biden announced that the government planned to offer booster shots starting the week of Sept. 20, according to Fox News.

Last week, as a response to confusing statements coming from both the Biden Administration and other health organizations like Centers for Disease Control (CDC) and Advisory Committee on Immunization Practices (ACIP), two FDA officials announced that they will be leaving their positions.

"It's a combination of things where the messaging is coming out of the White House and not of the FDA, and also out of the NIH with Tony Fauci and Dr. Francis Collins has said, 'Hey, we might have the vaccines for the 5 to 11 year olds in a couple of months' … well, FDA hasn't reviewed the data yet," Dr. Mark Siegel told America's Newsroom. "And with the boosters, the president himself said, 'We're going to get boosters in a month,' and the FDA says, 'Wait, we haven't reviewed the data yet.'"

CDC guidance currently recommends that immunocompromised people receive the booster shot.

"Although CDC does not recommend additional doses or booster shots for any other population at this time, HHS has announced a plan to begin offering COVID-19 vaccine booster shots this fall," the CDC states.

The FDA authorized both the Pfizer and Modern vaccines for booster shots in immunocompromised people, but added "Other fully vaccinated individuals do not need an additional vaccine dose right now."

"We have data now that when you give a third boost to either the Moderna or Pfizer it's very effective against any variant that we've tested, so that's the good news about our vaccines," Fauci explained. "If you get the level of antibody high enough, which booster's actually do, then you can feel pretty confident that you're going to be protected against virtually any variant."