United Airlines hasn’t had a Covid-related death among its nearly 70,000 employees in eight weeks, a trend its CEO says is due to the airline’s vaccine mandate.

United in August issued the strictest vaccine mandate among U.S. carriers: staff must be vaccinated against Covid or face termination. This fall, more than 96% of its staff was vaccinated, the company said.

Like in the rest of the country and at other airlines, Covid infections have surged among United staff, forcing the carrier to cut additional flights, a move United and other airlines have taken since late last year. About 3,000 United employees are positive for Covid, CEO Scott Kirby told employees late Monday. Zero are hospitalized, he said.

“Prior to our vaccine requirement, tragically, more than one United employee on average *per week* was dying from COVID,” Kirby wrote in a staff note. “But we’ve now gone eight straight weeks with zero COVID-related deaths among our vaccinated employees – based on United’s prior experience and the nationwide data related to COVID fatalities among the unvaccinated, that means there are approximately 8-10 United employees who are alive today because of our vaccine requirement.”

Other airlines didn’t immediately comment. United put its vaccine mandate in place before the Biden administration required federal contractors, like major airlines, to mandate vaccines or receive a medical or religious exemption for staff.