United Airlines' CEO Says Only a 'Handful' of Staff Have Resigned Over its Vaccine Mandate About 90% of United's US employees have shown proof of their vaccination, CEO Scott Kirby said.

United Airlines CEO Scott Kirby said he knows of fewer than 10 employees who have resigned over the company's vaccine mandate.

Kirby told CNN on Thursday that about 90% of United's US employees had shown the airline proof of their vaccination. He thought the majority of the remaining workers had been vaccinated but hadn't uploaded evidence yet, he said.

In August, United Airlines became the first US carrier to mandate vaccines for all US-based employees. Staff must be fully vaccinated no later than September 27 — a date five weeks after the Food and Drug Administration fully approved Pfizer-BioNTech's coronavirus vaccine.

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Speaking about how many employees had quit over the mandate, he said: "In a large company, it's a handful."

"The ones I'm aware of are in the single digit number of people," Kirby said. "We're going to have more by the time it finishes, but it's going to be a very low number of people."

Insider asked United to confirm exactly how many employees resigned over the vaccine mandate, but did not immediately receive a response.

Other airlines, including Alaska and Horizon, are only requiring the vaccine for new hires, while encouraging existing staff to get a shot by offering perks, such as bonuses.

Delta announced in August that it's requiring all employees to either get the COVID-19 vaccine or pay $200 extra a month for health insurance.

United's mandate preceded President Joe Biden's vaccine rules, announced September 9, requiring businesses with more than 100 employees to mandate vaccines or weekly testing. The administration has not said when this rule will take effect.