U.S. top infectious disease expert Anthony Fauci said Sunday that the U.S. may see "a surge upon a surge" of the coronavirus in the coming weeks after Thanksgiving, and he does not expect current recommendations around social distancing to be relaxed before Christmas.

Speaking on NBC's "Meet the Press" on Sunday, Dr. Fauci, director of the National Institute of Allergy and Infectious Diseases, said it was "not too late" for people traveling home after Thanksgiving to help curb the virus by wearing masks, staying distant from others and avoiding large groups of people.

As of Sunday, the number of COVID-19 cases recorded in November had surpassed 4 million, doubling the figure recorded in October. Since January, when the first infections were reported in the U.S., the nation's total number of cases has surpassed 13 million. More than 265,000 people have died.

Fauci told ABC's "This Week" that the level of infection in the U.S. would not "all of a sudden turnaround."

"So clearly in the next few weeks, we're going to have the same sort of thing. And perhaps even two or three weeks down the line. We may see a surge upon a surge," he said.

Thanksgiving often brings the busiest week for travel in the U.S. In 2019, it's estimated that 26 million people passed through the country's airports in the weeks surrounding the holiday.

During this year's Thanksgiving time, though people were warned more than once by health experts to stay home, anywhere from 800,000 to more than one million travelers made their way through U.S. airport checkpoints on any day, according to Transportation Security Administration statistics.

The number far surpassed that in early Pandemic days, when daily totals fell below 100,000 on some spring days.

"There is almost certainly going to be an uptick because of what has happened with the travel," Fauci was quoted by CNN as saying.

Other experts agreed that the coming weeks would be difficult, especially since so many traveled over the holiday and held in-person dinners indoors.

Dr. Deborah Birx, the White House coronavirus response coordinator, said Sunday on CBS' "Face the Nation" that Americans who traveled this past week should try to avoid people over 65. She said that those who were around others for Thanksgiving "have to assume that you were exposed and you became infected and you really need to get tested in the next week."

This coming week, the Advisory Committee on Immunization Practices reportedly will meet with the Centers for Disease Control and Prevention to discuss a rollout of the vaccine

The top infectious disease expert said the arrival of vaccines offers a "light at the end of the tunnel."

Health care workers will likely be among the first to get the vaccine, with the first vaccinations happening before the end of December, followed by many more in January, February and March, he said.

"So if we can hang together as a country and do these kinds of things to blunt these surges until we get a substantial proportion of the population vaccinated, we can get through this," Fauci said.

(With input from agencies)