American Airlines is joining a few different transporters in requiring its representatives to get vaccinated against COVID-19.

In a letter to representatives on Friday, Chairman and CEO Doug Parker and President Robert Isom said that workers situated in the U.S. what’s more, some worldwide group individuals would have to get vaccinated.

The leaders clarified that the prerequisite originated from the organization’s arrangement as an administration worker for hire because of its contribution in freight contracts with the Department of Defense and work with the City Pair and Civil Reserve Air Fleet projects. Last month, President Biden ordered COVID-19 antibodies for government laborers.

“While we are still working through the details of the federal requirements, it is clear that team members who choose to remain unvaccinated will not be able to work at American Airlines,” the two airline executives said in the staff memo. “Team members who cannot be vaccinated because of a disability or sincerely held religious belief can request an accommodation on Jetnet.”

Their letter didn’t determine a course of events for workers to be vaccinated, nor did it notice a possibility for representatives to get consistently tried. The leaders referenced that while the government mandate “may be difficult” for the individuals who picked not be vaccinated at this point against COVID-19, “it is what is required of our company, and we will comply.”

A few other airline organizations — JetBlue Airways and Alaska Airlines — have likewise recently let their representatives know that they will be needed to get the vaccine, given their work as government contractors. The two organizations are expecting workers to get the COVID-19 vaccine by Dec. 8.

In August, United Airlines became the first major carrier to require its 67,000 representatives to get vaccinated.

“We know some of you will disagree with this decision to require the vaccine for all United employees,” United CEO Scott Kirby and President Brett Hart wrote to staff in a memo at the time.

“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.”