There’sno indication when airlines’ normal schedules can resume.

Airlines canceled hundreds more flights Sunday, citing staff

problems tied to COVID-19, as the nation’s travel woes extended beyond Christmas, with no clear indication when normal sched

would resume.

More than 700 flights entering, leaving or flying within the U.S. were called off, according to the flight-tracking website FlightAware. That figure was down from nearly 1,000 on Saturday. More than 50 flights were already canceled for today.

Delta, United and Jetblue have blamed the omicron variant of the coronavirus for staffing shortages that forced cancellations.

“This was unexpected,” United spokesperson Maddie King said.

Globally, airlines scrapped about 2,200 flights as of Sunday morn

down from more than 2,800 from the day before, Flightaware’s data showed.

Jetblue scrapped 10% of its flights Sunday. Delta canceled 5% and United canceled 4%, according to Flightaware. The three airlines canceled more than 10% of their scheduled flights on Saturday. American Airlines spokesper

Derek Walls said the Christmas cancellations stemmed from virus-related sick calls.

The disruptions may extend into the New Year’s holidayweekend, said Henry Harteveldt, president of travel consulting firm Atmosphere Research Group. Still, U.S. air travel could face less stress if the federal government shortens the required quarantine for industry workers who test positive for the virus.

The Centers for Disease Control on Thursday reduced isolation time for vaccinated health care workers who contract the virus. Airlines for America, the trade association representing North American carriers, wrote to the CDC asking for the 10-day quarantine period for fully vaccinated individuals to be cut to “no more than five days.”

Flight cancellations are a “concern at a time when people are traveling to spend time with family and friends for the holidays,” Harteveldt said. “No airline wants to be viewed as the Grinch who stole Christmas.”

Also Sunday, the nation’s top infectious disease doctor acknowledged that he was frustrated with the limited supply of COVID-19 tests.

Demand for tests has risen amid the surge fueled by omicron.

“We’ve obviously got to do better,” Dr. Anthony Fauci said on ABC’S “This Week.”

“I think things will improve greatly we get into January, but that doesn’t help us today and tomorrow,” Fauci said.