Delta Air Lines said Wednesday 90% of its workforce of about 80,000 people have been vaccinated against Covid-19, weeks before the company imposes a $200 monthly insurance surcharge on staff who haven’t gotten shots.

The Atlanta-based airline’s CEO Ed Bastian earlier this month said about 85% of its staff was vaccinated.

On Wednesday, Bastian said he expected that rate to rise to about 95% by early November.

The latest tally, disclosed in its quarterly earnings release, comes as airlines are grappling with the Biden administration’s rules that federal contractors’ employees must be vaccinated against Covid, unless they can show a valid religious or medical reason to be exempt.

American Airlines, Southwest Airlines, JetBlue Airways and Alaska Airlines, which like Delta are federal contractors because they fly government employees and provide other services, in recent weeks have told staff they will comply with the mandate and that employees need to be vaccinated to continue working there, unless they receive an exemption. That means staff needs to be fully vaccinated by Dec. 8.

Delta hasn’t made such an announcement to staff.

Delta’s plan “is working and I’m proud of the people stepping up and making the right decision,” Bastian said in an interview with CNBC’s Squawk Box on Wednesday. “We haven’t done it with a mandate. We have done it working collaboratively with our people, trusting our people to make the right decisions for themselves, respecting their decisions, but at the same time avoiding the divisiveness of what the mandate is posing to society.”

Pilots unions at Southwest and American, which each say they are not anti-vaccine, have fought the mandate. The Allied Pilots Association, American’s pilots’ union, wrote to the White House and lawmakers last month asking for exemptions for pilots, while Southwest’s pilots’ union asked a court in Texas last week to block its implementation.

United Airlines issued its own company mandate in August, threatening to fire people who weren’t vaccinated by Sept. 27. More than 96% of its U.S. employees are now vaccinated, it said.

On Tuesday, Texas-based carriers American and Southwest said they expected the federal vaccine mandate to supersede an order by Texas Gov. Greg Abbott that bars businesses and others from mandating the vaccine for employees.