Thousands of would-be travellers received the same troubling message Thursday: a last-minute cancellation of their Christmas Eve flight because of the recent spike of coronavirus cases.

United Airlines cancelled at least 150 flights scheduled to leave dozens of airports Friday — along with 44 more that were supposed to take off Saturday, according to Flight Aware. Other airlines, including Delta, JetBlue and Allegiant, did the same.

In Australia, dozens of flights were also canceled at airports in the major cities of Sydney and Melbourne as coronavirus cases in the country surged to their highest since the start of the pandemic.

The number of cancellations globally as of Friday morning added up to more than 2000, the Flight Aware website showed.

It was the latest blow to the holiday season caused mainly by the new and highly transmissible omicron variant, which now accounts for more than 70% of new coronavirus cases in the United States. Nearly 170,000 people are testing positive every day in the country, a 38% increase over the past two weeks, according to The New York Times’ coronavirus tracker.

In its statement, United said that omicron’s “direct impact on our flight crews and the people who run our operation” led to the cancellations. Crew members had been calling in sick, according to spokesperson Joshua Freed, who said that United alerted customers as soon as it could. And while Freed said he did not expect the airline to cancel more flights, it remained a possibility.

“We are really managing this day by day,” he said. “There may be some more flight cancellations for Saturday. It’s possible.”

In its statement, the airline said it was working to rebook as many people as possible in time for the holidays.

Customers took to social media to air their grievances about the cancellations.

In Australia, which has recorded more than 500 omicron cases, many airline staff members are unable to work after being identified as close contacts of positive coronavirus cases, airline officials said. Under government requirements, they are required to isolate for seven days.

“A large number of our frontline team members are being required to test and isolate as close contacts given the increasing number of cases in the general community,” a representative for Jetstar Airways said by email on Friday afternoon local time. “As a result, we have had to make some late adjustments to our schedule.”

Eighty flights arriving at and departing on December. 24 from Sydney, the country’s most populous city, had been canceled, a spokesperson for the airport said, out of a total of 500.

According to Melbourne Airport’s flight-tracking website, more than 70 flights departing or arriving from the airport on December 24 had also been scrapped, out of 700 flights. Brisbane Airport said that 45 flights had been cancelled.

New York Times News Service