Carrier estimates 593 workers didn’t get the shots Sept. 27 deadline

United Airlines Holdings Inc. is moving ahead with plans to terminate close to 600 employees who didn’t meet its Covid-19 vaccination deadline, company officials said Tuesday.

United in August said it would require all of its 67,000 U.S. employees to be vaccinated—the first major U.S. airline and one of the first large U.S. companies to do so.

Now the Sept. 27 deadline has passed, and while most of the airline’s employees complied, United is starting the process of firing 593 employees who didn’t get the shots, company officials said. Those workers can still save their jobs if they opt to get vaccinated in the coming days before their official termination meetings, airline officials said Tuesday.

“We know for some, that decision was a reluctant one,” United Chief Executive Scott Kirby and President Brett Hart wrote in a letter to employees Tuesday. “But there’s no doubt in our minds that some of you will have avoided a future hospital stay—or even death—because you got vaccinated.”

The potential terminations apply to United employees who chose not to get vaccinated. Another roughly 2,000 United employees have sought exemptions for religious or medical reasons, company officials said.

United had planned to put employees who received those accommodations on unpaid leave starting Oct. 2, but has postponed that until Oct. 15 while it contends with a lawsuit challenging the accommodations it has offered to such employees. Six United employees sued the airline last week in federal court in Texas, alleging that by only offering unpaid leave, the company was discriminating against employees who have a religious objection to receiving the vaccine, or who qualify for accommodations on medical grounds.

The airline is disputing the lawsuit, and a hearing is scheduled for Oct. 8.

U.S. airlines have taken different approaches when it comes to employee vaccinations. Starting in November, Delta Air Lines Inc. will require unvaccinated employees to pay an extra $200 a month for their company health insurance. The airline has said its vaccination rate had been climbing since it rolled out the policy, with 82% of its workers now vaccinated, up from 72% in July.

Carriers including Southwest Airlines Co. and American Airlines Group Inc. so far have tried to encourage workers to get vaccinated voluntarily, but they haven’t required it. That could change; the Biden administration this month laid out plans for new rules governing vaccination for large companies and government contractors. It isn’t known whether airline workers would have the option of undergoing regular testing in place of vaccination under the administration’s plans.

Pilots at both airlines have said they oppose vaccine mandates. In a letter last week to federal officials, the union that represents American Airlines pilots said labor shortages and operational problems could arise for airlines during the holiday-travel season if vaccinations were strictly required. They asked that unvaccinated pilots be allowed to keep flying if they are tested regularly. The union has said about 70% of American’s pilots are vaccinated.

At United, 20 pilots refused to be vaccinated, and roughly 330 asked for accommodations, according to a message from the pilots union, which said it would bring a grievance to contest how the mandate is being implemented for the handful of pilots who wouldn’t comply. Fewer than 100 flight attendants refused to be vaccinated, according to the flight attendants’ union.

Michael Klemm, district president of the union that represents some 25,000 United customer-service workers, ramp workers and others, said his members were divided. Nearly half were unvaccinated before the new requirement was announced, Mr. Klemm said. Some wanted to be sure their co-workers were vaccinated, while others wanted to have the choice, Mr. Klemm said.

In the end, roughly 350 workers in the union refused to comply, and another 700 sought exemptions, he said.