Dr. Anthony Fauci, the nation's top infectious diseases expert, said Sunday that the U.S. is "struggling" the get the coronavirus outbreak under control and warned Americans to prepare for the coming week "to be a bad week."

"So on the one hand, things are going to get bad, and we need to be prepared for that," Fauci, director of the National Institute of Allergy and Infectious Diseases, said on CBS News' "Face the Nation."

"It's going to be shocking to some. It certainly is really disturbing to see that. But that's what's going to happen before it turns around," he said. "So just buckle down, continue to mitigate, continue to do the physical separation, because we've got to get through this week that's coming up, because it is going to be a bad week."

He added: "I will not say we have it under control. ... That would be a false statement. We are struggling to get it under control. And that's the issue that's at hand right now. The thing that's important is that what you see is increases in new cases, which then start to flatten out."

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Fauci said the death toll will lag behind a curbing of confirmed cases anywhere from one to two weeks or possibly longer.

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"But the end result of that you don't see for days or weeks down the pike, because, as the cases go down, then you get less hospitalizations, less intensive care and less death," Fauci said. "So even though you're getting really an improvement in that the number of new cases are starting to flatten, the deaths will lag by one or two weeks or more. So we need to be prepared that even though it's clear that mitigation is working, we're still going to see that tail-off of deaths."

As of Sunday evening, more than 9,400 people have died in the U.S. because of the coronavirus pandemic, with more than 332,000 confirmed cases, according to an NBC News count. Experts anticipate that the virus could kill more than 100,000 Americans while infecting millions more.

The vast majority of governors have imposed stay-at-home orders to curb the spread of the highly contagious virus. On Friday, the Centers for Disease Control and Prevention also recommended for the first time that Americans wear masks when in public settings.

Speaking Sunday on NBC's "Meet the Press," Surgeon General Jerome Adams said the coming week "is going to be our Pearl Harbor moment, it's going to be our 9/11 moment, it's going to be the hardest moment for many Americans in their entire lives."

"And we really need to understand that if we want to flatten that curve and get through to the other side, everyone needs to do their part," he said.

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Fauci said on "Face the Nation" that the U.S. needs "to be prepared that since [COVID-19] is unlikely to be completely eradicated from the planet, that as we get into next season, we may see the beginning of a resurgence."

Fauci said the disease may become "seasonal" in nature.

"And that's the reason why we're pushing so hard in getting our preparedness much better than it was, but importantly, pushing on the vaccine and getting clinical trials for therapeutic interventions so that hopefully, if we do see that resurgence, we will have interventions that we did not have in the beginning of the situation we're in right now," he said.

Fauci said, "We should hope that within a week, maybe a little bit more, we're going to start to see a flattening out of the curve," adding that the mitigation efforts are "absolutely key to the success of that."