Nearly 96% of United's U.S. employees were vaccinated against Covid-19 before the Sept. 28 deadline.
An additional 3% of United employees applied for an exemption from the company's vaccine mandate for religious or medical reasons. This leaves 593 employees who will be terminated as soon as Wednesday.
A United spokesperson said that the firings would not affect airline operations in a press conference on Tuesday.
In a letter to employees, Scott Kirby, CEO of the carrier, described the mandate program in the company's "historic achievement".
He wrote, "Everyone is safer if everyone is vaccinated and the vaccine requirements work."
United is the largest U.S. carrier that has implemented a mandate for vaccines for employees. It was also the first. Hawaiian requires all employees to be vaccinated.
The airline will allow employees who have applied for exemption to continue working until Oct. 15, if United does not respond to a legal challenge.
A spokesperson for the company stated that the mandate had helped recruiters since it was announced by the carrier in August.
The spokesman stated that United has received applications from many highly qualified candidates in response to this requirement.
