Delta Air Lines CEO Ed Bastian said about 8,000 of its 75,000 employees tested positive for Covid-19 over the last four weeks, absences that marred the company’s financial results during a busy holiday travel season.

Delta reported a loss for the quarter and forecast another for the first three months of the year because of the fast-spreading omicron variant, but predicted travel would begin to rebound again in late February.

A series of winter storms and airline crews sidelined by omicron infections contributed to more than 20,000 U.S. flight cancellations industry-wide between Christmas Eve and the first week of January. United Airlines CEO Scott Kirby on Monday said 3,000 of its close to 70,000 U.S. employees were positive for Covid.

Flight cancellations have eased significantly in the past few days. Delta’s operation has since stabilized said on Thursday, with 1% of flights canceled over the past week because of omicron.

The employees who tested positive had “no significant health issues,” Bastian said in an interview with CNBC’s “Squawk Box” after releasing quarterly results.

Delta late last year updated its sick-leave policy for employees who test positive for Covid-19, providing them five days of pay, outside of sick banks, and an additional two days if they test positive on the fifth day. Previously staff had 10 days of paid leave. That came after the Centers for Disease Control and Prevention updated its guidelines for Covid quarantining, halving its recommendation to five days.

Delta and other airlines had urged the CDC to make the change.

The largest U.S. flight attendant union criticized Delta’s policy. Sara Nelson, president of the Association of Flight Attendants tweeted last week that Delta “is telling workers across work groups that they should come to work w/ symptoms even if someone in the household tested positive.” She also said that positive workers were told to “come to work after 5 days if the fever is below 100.9, even if still testing positive.”

Delta issued a cease-and-desist letter over the comments to the union, which is trying to organize Delta’s flight attendants.

Bastian defended the policy and said it was based on CDC guidance.