By CBSBoston.com Staff

BOSTON (CBS) — Travel this Christmas season has surpassed pre-pandemic levels, but two major airlines were forced to cancel over 300 Christmas Eve flights as COVID-19 hits their crews.

United and Delta have confirmed they had to cancel flights because of Omicron and staffing shortages.

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“The nationwide spike in Omicron cases this week has had a direct impact on our flight crews and the people who run our operation,” a United Airlines spokesperson told CBS News in a statement. “As a result, we’ve unfortunately had to cancel some flights and are notifying impacted customers in advance of them coming to the airport.”

United had 175 cancellations on Friday, while Delta canceled about 150 flights.

“Delta teams have exhausted all options and resources — including rerouting and substitutions of aircraft and crews to cover scheduled flying,” the airline said in a statement.

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Travelers out of Boston also experienced some issues. There were at least 35 cancellations out of Logan Airport on Christmas Eve and more than 100 delays.

The TSA says passenger volume at Logan is up 58% from last year. Thursday was the busiest day of the week at the airport, with more than 50,000 passing through security.

“I’m very scared to be flying to be honest,” Ashley Clark said. “I’m glad to see everyone looks pretty masked up. I just hope people on the plane are respectful of those around them.”

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Health experts tell WBZ-TV that airline passengers are more likely to get COVID because of the Omicron variant. If people must travel, they are urged not to take their mask off during the flight at all if possible.

CBSBoston.com Staff