The surge in COVID-19 cases around the world has forced the airline industry to cancel over 2,000 flights on Monday.   

More than 700 flights within, into or leaving the U.S. were canceled, according to CNN. People trying to fly during the busy holiday weekend were also hit with extensive delays, with more than 3,000 flights being postponed.   

“The nationwide spike in Omicron cases this week has had a direct impact on our flight crews and the people who run our operation,” United Airlines said in a memo obtained by CNN.   

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According to the U.S. Transportation Security Administration, 2.19 million people traveled on Dec. 23, but fewer people, around 1.53 million on Christmas Day, traveled, largely in part because of the cancelations.   

More than 2,300 U.S. flights were canceled on Saturday and Sunday.   

The omicron variant is the most dominant variant of the virus, with more than 70% of new COVID-19 cases stemming from omicron, The New York Times reported. The U.S. is averaging 200,000 cases a day, the highest number in close to a year.   

“Swift and safe adjustments by the CDC would alleviate at least some of the staffing pressures and set up airlines to help millions of travelers returning from their holidays,” Derek Dombrowski, a JetBlue spokesman, told the Times.   

Despite the increase in cases and influx of flight cancelations, airlines expect millions of people to travel on Jan 2.