NEW YORK — Airlines have canceled more than 4,500 flights during the Christmas weekend, as the Omicron variant of COVID-19 forces itinerary changes and holiday travel plans worldwide.

According to Flightaware, there were at least 2,000 cancelations on Saturday morning, with about 700 of those coming from the US.

On Friday, more than 2,400 cancelations and 11,000 delayed flights were reported by the flight tracking website. Another 600 canceled flights were already announced for Sunday.

The cancelations caused a major disruption to the return to Christmas travel this year, causing further anxiety and uncertainty after the 2020 holiday season was severely affected by the pandemic.

The most recent surge in COVID-19 cases and the rapid spread of the Omicron variant created a host of issues for airlines like Lufthansa, Delta and United Airlines, including staff shortages as more and more pilots and cabin crew members reported ill with the virus or were forced to quarantine on arrival in certain countries.

Chinese airlines have been hit the hardest — China Eastern alone reported 480 flight cancelations, or more than 20 percent of its planned flights. Air China cancelled around 15 percent of its scheduled departures.

United Airlines explained in a statement that the spike in Omicron cases “had a direct impact” on their flight crews and the people who run their operations.

“As a result, we’ve unfortunately had to cancel some flights and are notifying impacted customers in advance of them coming to the airport,” the company said. — Euronews