(NEXSTAR) — Are you one of the millions of people who traveled during the Thanksgiving holiday?

Then you should “assume you were exposed” to COVID-19, according to Dr. Deborah Birx, the White House’s coronavirus task force coordinator.

“If your family traveled, you have to assume you were exposed and you became infected, and you really need to get tested in the next week, and you need to avoid anyone in your family with comorbidities or are over 65,” she told CBS’ “Face the Nation” on Sunday.

Ahead of the holiday, the Centers for Disease Control and Prevention urged Americans to refrain from traveling or gathering with people outside their household.

And Dr. Anthony Fauci, the nation’s top infectious disease expert, warned on ABC’s “This Week” before the holiday that “we may see a surge upon a surge” of coronavirus cases.

Now that the holiday is over, what should people do if they traveled or gathered for Thanksgiving?

Birx recommends wearing a mask indoors. “If you’re young and you gathered,” she said, “you need to assume that you’re infected and not go near your grandparents and aunts and others without a mask.”

Fauci recommended that travelers quarantine once they return home. He also stressed the importance of masking and social distancing. He said such actions can “blunt” surges in virus cases.

The CDC said people quarantining after possible exposure should stay home for 14 days after the last contact with a person who has the virus, watch for symptoms and stay away from others, especially those who are more vulnerable.

If you’re over 65 or have underlying health conditions and you gathered at Thanksgiving, keep an eye out for symptoms, Birx said.

“If you develop any symptoms, you need be tested immediately because we know that our therapeutics work best — both our antivirals and our monoclonal antibodies — work best very early in disease,” she said.

The CDC says symptoms may appear two to 14 days after exposure to the virus.

Also, experts say, be aware that the coronavirus takes three to four days to incubate, so getting a test immediately after possible exposure may not return accurate results, so waiting a few days may be the way to go.

As of Monday, at least 1,265 new coronavirus deaths and 167,759 new cases were reported in the U.S., according to The New York Times, and there has been an average of 160,387 cases per day over the past week, a 3% increase from the average two weeks earlier.