• Delta says about 90% of its roughly 80,000 employees are vaccinated.
• The Atlanta-based airline plans to charge unvaccinated employees $200 more a month for health care starting Nov. 1.
• Rivals American and Southwest are mandating vaccines under a Biden administration rule for federal contractors.

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's Bastian said its own plan is working.

"We haven't done it with a mandate," Bastian said in an interview Wednesday on CNBC's "Squawk Box." "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.

"I think the spirit of the [federal] mandate was to get people vaccinated. It wasn't to try to force people with the threat of their jobs if companies are doing the right thing," Bastian said.

Delta in August announced that it will raise health insurance premiums by $200 a month for staff that aren't fully vaccinated by Nov. 1, citing rising health insurance costs. Bastian told employees at the time it costs the company, which self-insures its employees, an average of $50,000 every time an employee is hospitalized for Covid.

"All Delta employees who have been hospitalized with COVID were not fully vaccinated," he said at the time.

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.