Long lines were seen at Chicago's O'Hare Airport Tuesday as the the busy holiday travel rush began this week with COVID cases rising across the U.S.
Photos and video from the airport showed crowds of people lined up at bag drops and in security.
Between the city's two airports - O'Hare and Midway - about 3 million travelers are expected between now and Jan. 3.
In total, AAA predicts more than 100 million people will hit the roads, sky and other forms of transportation over the Christmas holiday.
The Transportation Security Administration reported just over 2 million travelers on Saturday alone. That's well over the just over 1 million reported for the same day in 2020, but short of the 2.4 million seen in 2019.
United Airlines said it expects 8 million people will fly between Dec. 16 and Jan. 2, more than double the number of travelers from the same time last year and about 87% compared to in 2019.
At O'Hare Airport alone, the airline expects 72,000 passengers will fly on its busiest travel day, Dec. 23.
But some experts say demand has started to slow.
"You can see however in the numbers that the comfort and the level of confidence in travel is dropping, but not as steep as we've seen in 2020," Trivago CEO Axel Hefer told NBC News.
COVID is once again surging in many parts of the country, with deaths now topping 800,000 in the U.S.
In Chicago, a travel advisory remains in effect with 42 states and Washington D.C. on the warning list for travelers. The advisory is expected to be updated once more before the Christmas holiday on Tuesday.
But while the new omicron variant has many top health officials concerned, Dr. Anthony Fauci, the country's leading infectious disease expert, said the U.S. is in a better position now than it was last year thanks to the expansion of vaccines, which are now available for a wider range of ages, including children as young as 5.
The Biden administration is expecting a series of breakthrough infections with the surge of holiday travelers. Fauci said most people who have been vaccinated and gotten a booster should be fine if they take precautions such as wearing masks in crowded settings including airports.
Local health experts agreed.
"You want to be safe during the time that you're traveling if you're on an airplane," said Dr. Robert Citronberg, medical director for infectious disease at Advocate Aurora Health.
He added that being safe at your destination is also equally as important.
"You want to just try to, as best as possible, avoid large crowds and maybe even more important is just to surrounding yourself with people that you know to be fully vaccinated," he said.
So what should those traveling keep in mind this holiday season?
"I think the most important thing to remember is how and when to use testing to your advantage," Dr. Natalie Azar, a medical contributor for NBC News said. "The idea is that you want to do a test really within a few hours of meeting with a family or friends or folks outside of your household."
If you're re-thinking holiday travel plans, cancellation policies vary based on the type of ticket purchased and airlines.
Some, like Delta Airlines, temporarily removed change fees during the pandemic.