United Airlines announced it would require its employees in the United States to receive an approved COVID-19 vaccination by October 25 or face termination.

According to The Washington Post , United CEO Scott Kirby and President Brett Hart announced the airline would become the first to require each of the company’s 67,000 U.S. employees to be fully vaccinated.

The carrier previously offered incentives to existing employees who received the vaccine, including bonuses and days off , and now requires all newly hired workers to show proof of vaccination.

“We know some of you will disagree with this decision to require the vaccine for all United employees,” Kirby and Hart said in a note to employees obtained by The Washington Post. “But we have no greater responsibility to you and your colleagues than to ensure your safety when you're at work, and the facts are crystal clear: everyone is safer when everyone is vaccinated.”

In January, Kirby began advocating for all airlines to adopt a policy that would mandate COVID-19 vaccines for all employees, something experts believe would happen now that United was the first to implement a vaccination mandate.

The carrier revealed that employees must upload proof of a full vaccination before October 25, but said exceptions would be made for certain health issues or religious reasons. The mandate will not apply to United’s regional airlines.

“Over the last 16 months, Scott has sent dozens of condolences letters to the family members of United employees who have died from COVID-19,” Kirby and Hart continued. “We're determined to do everything we can to try to keep another United family from receiving that letter.”