DENVER (KDVR) — Monday was the deadline for United Airlines employees to get the COVID-19 vaccine — or else.  

On Aug. 6., United Airlines gave their employees notice that the company was requiring its workforce to get vaccinated, and that there would be consequences for those who didn’t.  

United Airlines told NewsNation affiliate KDVR that more than 97% of company employees were vaccinated just ahead of the Sept. 27 deadline, aside from a small number who submitted exemptions. For those who have yet to receive at least one shot, and have not been granted an extension, United has said it will start “the separation process” as early as Sept. 28.

“While we continue to be encouraged by the outpouring of support and appreciation that we’ve received from employees, we know the decision to get vaccinated was a difficult one for some. But we also know that everyone is safer when everyone is vaccinated. And vaccine requirements work,” a spokesperson for the airline previously said.

Still, six United Airlines employees are asking a federal judge to block the airline’s vaccine requirement. The employees, including two pilots and a flight attendant, are accusing the airline of a “pattern of discrimination” against employees who requested religious or medical accommodations. They claim the policy violates the Americans with Disabilities Act and Civil Rights Act. 

Aside from United, Frontier Airlines and Hawaiian Airlines have previously said they would also will require all employees to get COVID-19 vaccinations by Oct. 1 and Nov. 1, respectively, or show proof of a negative COVID-19 test on a regular basis. Alaska Airlines, too, said it was looking into vaccine requirements “closely.”

Delta Airlines, meanwhile, said it would require vaccines for all new hires and now has implemented a $200 monthly surcharge for employees on the company health plan who don’t get the vaccine. The airline later confirmed that at least a fifth of its unvaccinated employees decided to get the shot.