Washington CNN  — 

Dr. Anthony Fauci said Sunday that it’s “possible” Americans will still need to wear masks in 2022 to protect against the coronavirus, even as the US may reach “a significant degree of normality” by the end of this year.

Asked by CNN’s Dana Bash on “State of the Union” whether he thinks Americans will still need to wear masks next year, Fauci replied: “You know, I think it is possible that that’s the case and, again, it really depends on what you mean by normality.”

The comments from Fauci come as the US Covid-19 death toll approaches 500,000 and the country nears a full year in its fight against the virus. And though the US is now steadily rolling out vaccines to fight the pandemic, the nation’s top infectious disease expert underscored the importance of mitigation measures to fight the aggressive virus and its emerging variants as many Americans express pandemic fatigue.

Fauci told Bash that while he can’t predict when the US might return to operating as it did before the pandemic told hold, he thinks that by the end of this year “we’re going to have a significant degree of normality beyond the terrible burden that all of us have been through over the last year.”

“As we get into the fall and the winter, by the end of the year, I agree with (President Joe Biden) completely that we will be approaching a degree of normality,” said Fauci, who serves as Biden’s chief medical adviser.

Mask-wearing is critical to slowing the spread of the virus, according to the US Centers for Disease Control and Prevention, which says they can help protect both the people wearing them and those around them from transmitting the virus.

The Biden administration has been pushing mask-wearing more aggressively than the Trump administration did, with the President signing an executive order last month mandating interstate travelers wear a mask and requiring masks on federal property. Biden also challenged Americans to wear masks for the first 100 days of his presidency to reduce the spread of the virus.

Fauci also weighed in Sunday on suggestions by researchers in Israel in Canada that just one dose of the Pfizer/BioNTech vaccine was needed to protect against the virus, saying “the science points directly towards continuing with what we know about from the clinical trial,” which is that two doses provide the most protection against the virus and the emerging variants.

“We know for sure that when you give a prime with the Pfizer followed by a boost 21 days later that you get a 94% to 95% efficacy and the difference between the level of antibodies after one dose versus two doses is about tenfold higher,” he said.

“And that is really important because when you have that high a degree comparable to the single dose alone, that’s the cushion that you would like to have when you get a variant that isn’t as well-protected against by the antibodies induced by the vaccine, but you have enough level to be able to prevent at least severe disease.”

This story has been updated with additional details Sunday.

CNN’s Maggie Fox and Gregory Wallace contributed to this report.