LONDON — Deborah Tudhope was growing anxious. An American lawyer living in London, she was hoping to fly back to the United States in two weeks to see her 96-year-old mother, who lives in a retirement home in Maine. But the Omicron-driven travel restrictions announced on Thursday by the White House have her worrying that the trip may not happen.
Ms. Tudhope, 72, has had to reschedule her required coronavirus test for the day before her flight, which the airline had already pushed back a day. With the rules seemingly shifting by the hour, she said she faced multiple hurdles: getting out of Britain, getting into the United States and visiting her mother in the home.
“I don’t know how this whole thing is going to work out,” said Ms. Tudhope, who described herself as disheartened, if not surprised, by the turmoil. “But I did make sure the flights are re-bookable.”
Such private dramas are playing out all over the world, as thousands of people — Americans living abroad and foreigners hoping to visit the United States — grapple with the new complexities of holiday travel in the age of Covid.
The spread of the Omicron variant in the last week has injected even more uncertainty into an already fraught exercise. On Thursday the Biden administration shortened the time frame for international travelers to the United States to take a Covid test within a day before departure, regardless of vaccination status.
That has left would-be travelers nervously calculating whether they will get test results back in time to make their flights or worrying that their home countries could impose more stringent travel bans while they are away.
The United States stopped short of imposing a mandatory seven-day quarantine on arrivals, which many travelers said would have torpedoed their plans. Nor did it upgrade its standard for an acceptable Covid screen from an antigen to a P.C.R. test, which can take significantly longer to produce results.
But the new one-day window for getting tested announced by the Centers for Disease Control and Prevention has nevertheless added an extra layer of preflight stress.
Paula Tolton, 23, an American student in Taipei, Taiwan, who plans to fly home next month to visit her family in Jacksonville, Fla., said she was worried that the new rules could cause her to miss her flight. Even the previous testing requirement for the United States, a negative result on a P.C.R. test within three days of arrival in the country, triggered “anxiety to the max,” she said.
“I’ve had that stress before when a P.C.R. test didn’t come back when I was supposed to fly in April,” she said. “I was freaking out.”
Public-health experts said there was a sound reason to shorten the time frame for test results: it would detect more infections in travelers. And since the results for antigen tests are normally available within a few hours, it should be possible to take a test and get the results within the prescribed period.
“A negative test is a good idea, especially since fully vaccinated people can transmit the virus,” said Devi Sridhar, head of the global public health program at the University of Edinburgh. But she acknowledged that the…