• The worst of the coronavirus outbreaks sparked by people who traveled for Thanksgiving hasn't yet occurred, Dr. Anthony Fauci said Tuesday.
• The country could see "the full brunt" from the virus coming off the Thanksgiving season at some point next week, he said.
• The worsening outbreak would come as people begin to travel and gather for the Christmas season, Fauci said.

As Christmas nears, the U.S. has yet to see the worst from the coronavirus outbreaks driven by people traveling and congregating for Thanksgiving, White House coronavirus advisor Dr. Anthony Fauci said on Tuesday.

"That should be sometime probably next week or a week and a half," Fauci told The Wall Street Journal's CEO Council summit in regard to when the United States could expect "the full brunt" from the virus coming off the Thanksgiving holiday season.

"And then we're going to enter into the Christmas season, again with more traveling and with more congregating at family and social gatherings. So we're in for a very challenging period," Fauci said.

The U.S. is now reporting a record 201,154 Covid-19 cases daily, based on a weekly average, according to a CNBC analysis of data compiled by Johns Hopkins University. That figure is an increase of more than 25% compared with a week ago.

The nation's hospitals are also reporting a record number of patients — 102,148 people — sickened with Covid-19, a sign that the outbreak is growing more severe, according to data from the COVID Tracking Project, which is run by journalists at The Atlantic.

Fauci has previously warned that the U.S. could see a "surge upon a surge" of Covid-19 cases following Thanksgiving and heading into Christmas. The month of December could be a time of "precarious risk" as some people begin shopping for Christmas gifts in stores and host ill-advised parties for New Year's Eve, he said last week.

Covid-19 cases were already on the rise before Thanksgiving when the U.S. Centers for Disease Control and Prevention warned against traveling for the holiday. Despite those warnings, more than 3 million people traveled through the nation's airports, marking the busiest travel weekend since lockdown orders hit in mid-March. The CDC now advises that people avoid traveling and gathering through the winter holidays.

The worsening outbreak has spurred some state and city leaders to implement more restrictions to prevent overcrowding their intensive care units.

In California, Gov. Gavin Newsom announced last week that the state would impose a stay-at-home order on regions if their hospitals' available ICU capacity fell below 15%. Last week, Fauci said that parts of the country could see more temporary restrictions like those in California.

On Tuesday, Fauci said that he will push for a more uniform national public health approach to help thwart outbreaks when he meets with President-elect Joe Biden's team. Those methods include widespread use of face masks, social distancing, frequent hand washing and avoiding gatherings, especially indoors, he said.

However, the U.S. hasn't adhered to those measures uniformly, which is "really extraordinarily frustrating," Fauci, who will join Biden's team as an advisor once the president-elect is sworn in, said.

"Trouble is, you go to different parts of the country and even when the outbreak is clear and hospitals are on the verge of being overrun, there are a substantial proportion of the people who still think that this is not real. That it's fake news or that it's a hoax," Fauci said Tuesday.

"It's extraordinary," he said. "I've never really seen anything like this."

— CNBC's Will Feuer and Nate Rattner contributed to this report.