Tens of millions of people are expected to travel to family gatherings or winter vacations over Christmas, despite pleas by public health experts who fear the result could be another surge in COVID-19 cases.

In the U.S., AAA predicts that about 85 million people will travel between Dec. 23 and Jan. 3, most of them by car. If true, that would be a drop of nearly one-third from a year ago, but still a massive movement of people in the middle of a pandemic.

Jordan Ford, 24, who was laid off as a guest-relations worker at Disneyland in March, said he plans to visit both his and his boyfriend’s families in Virginia and Arkansas over Christmas.

“It is pretty safe — everyone is wearing a mask, they clean the cabin thoroughly,” said Ford, who has traveled almost weekly in recent months from his home in Anaheim, California, and gets tested frequently. “After you get over that first trip since the pandemic started, I think you’ll feel comfortable no matter what.”

Experts worry that Christmas and New Year’s will turn into super-spreader events because many people are letting down their guard — either out of pandemic fatigue or the hopeful news that vaccines are starting to be distributed.

“Early on in the pandemic, people didn’t travel because they didn’t know what was to come,” said Dr. Peter Chin-Hong, an infectious-disease expert at the University of California, San Francisco, “but there is a feeling now that, ‘If I get it, it will be mild, it’s like a cold.’”

The seven-day rolling average of newly reported infections in the U.S. has risen from about 176,000 a day just before Thanksgiving to more than 215,000 a day. It’s too early to calculate how much of that increase is due to travel and gatherings over Thanksgiving, but experts believe they are a factor.

The Centers for Disease Control and Prevention says “postponing travel and staying home is the best way to protect yourself and others from COVID-19.” People who insist on travel should consider getting tested for the virus before and after their trip and to limit non-essential activities for seven days after travel with a negative test result and 10 days if they don’t get tested.

Other countries have imposed restrictions ahead of the holidays. Last month, England, Scotland, Wales and Northern Ireland agreed to permit a maximum of three households to mix between Dec. 23 and Dec. 27, regardless of what local restrictions are in place.

Germany’s ADAC motoring association says that holiday traffic will be sharply reduced. The reasons include not only caution and government urging to avoid personal contact, but also the simple fact that many traditional destinations, from the country’s enchanting Christmas markets to the Alpine ski resorts, have been ordered closed.

Christmas markets, which normally draw large crowds to city centers for steaming mugs of mulled wine, have been canceled; a lockdown imposed Dec. 9 closed retail deemed nonessential.

Meanwhile, the usual pilgrimage via autobahn to the ski slopes, which typically begins on Dec. 26, will be largely absent since France, Germany and Italy have ordered ski resorts closed. Borders are open but with significant limits such as quarantine requirements.

In Latin America, a few countries have imposed some restrictions to try to keep people from traveling or meeting during the holidays, but others advised people only to practice social distancing and skip parties.

Panama has some of the strictest measures, including a curfew through Jan. 4 and a prohibition on leaving home at all from Dec. 25 to 28 and Jan. 1 to 4 unless it’s for essential activities such as buying food or medicine. Peru, one of the region’s hardest-hit countries, has banned the use of private cars on Christmas Eve and Day and New Year’s Eve and Day in hopes of discouraging people from traveling.

In the U.S., Rachel Watterson delayed her New Year’s Eve wedding because her fiance’s family can’t travel to the United States from their home in Germany. Instead, the couple plans to elope and will fly from their home in Chicago to Hawaii with her parents, her brother and a friend. They picked Hawaii because of requirements that include coronavirus testing before arrival and a rapid test at the airport.

“We felt this was one of the very few safe choices we can make if we are going to travel,” Watterson said.

Tim Brooks, a 37-year-old engineer in Long Beach, California, canceled a trip to Grand Cayman because of a ban on international visitors, then scrapped a Christmas visit to his parents in North Carolina as infections spiked in California and around the country.

“If it were just us, it wouldn’t be so bad, but we have older parents and we are trying to keep them safe,” Brooks said.

Airports and planes will be far less crowded this year in what is normally a high travel season. So far in December, air travel in the United States is down 67% from last year. If Thanksgiving is any indication, the number of travelers will rise the rest of the month, but airlines are warning that bookings have slowed down since the latest surge in COVID-19 cases.

The nation’s top four airlines now show December and January schedules that are anywhere from 33% to 46% smaller than a year earlier, according to figures from Airline Data Inc.

Last week, the average flight within the U.S. was only 49% full compared with more than 80% full a year ago, according to the trade group Airlines for America.

The short-term outlook remains grim for other travel-related businesses, including those that rely on winter tourism.

In Vermont ski country, the Trapp Family Lodge in Stowe is usually sold out during Christmas week, but only half the 96 rooms were booked by last week. It was a similar story at the nearby Lodge at Spruce Peak. Operators of both lodges blamed travel restrictions, especially quarantine requirements that are triggered by crossing state lines.

“It is frustrating as a business to basically be forbidden to do your job and to not be able to support your employees or your community,” said Sam von Trapp, executive vice president of the family’s lodge. “At the same time we understand that there is very good intention behind all these restrictions.”

Cruise ships often command their highest prices at Christmas and other holidays when kids are off school, but few ships are sailing this season. Carnival, Royal Caribbean, Norwegian and Disney have all cancelled U.S. sailings through Feb. 28. Voyages in other parts of the world have mostly been delayed.

Florida, which relies heavily on winter tourism, is also taking a big hit. The two-week period around Christmas is normally the busiest time of year for Walt Disney World in Orlando, says Len Testa, the president of TouringPlans.com, which forecasts park attendance. But this year, the Magic Kingdom has capped park attendance at 35%, so Testa only expects around 32,000 people on those days.

Testa also expects crowd levels to be lower than usual from January through March, with many visitors rescheduling their trips to May or later.

“Many families will put off their Spring Break trips until they’re vaccinated,” he said.

Tara Kelley had planned to drive seven hours from her home in Milligan, Florida, to Orange City, Florida, to visit her mother and stepfather for Christmas. But Kelley’s wife recently had surgery and spent a day at a hospital where there was a risk of exposure to the coronavirus, so they called off the trip.

“We had literally been planning this since February,” Kelley said. “It’s a blow.”

Theresa Medina, a 55-year-old retiree from South Boston, is still deciding whether she and her husband will visit his mother in the Dominican Republic this winter. She’s 80% sure they will, and she’s already packing a box to ship ahead of their arrival. But the couple plans to discuss it with her husband’s doctor in January.

If they go, Medina said they will get coronavirus tests and wear protective gear, including face shields and masks.

“We may look silly on the plane, but precautions are precautions,” she said.