Delta Air Lines will charge employees on the company health plan $200 a month if they fail to get vaccinated against COVID-19, a policy the airline’s top executive says is necessary because the average hospital stay for the virus costs the airline $40,000.

CEO Ed Bastian said that all employees who have been hospitalized for the virus in recent weeks were not fully vaccinated.

The airline said today that it also will stop extending pay protection to unvaccinated workers who contract COVID-19 on Sept. 30, and will require unvaccinated workers to be tested weekly beginning Sept. 12, although Delta will cover the cost. They will have to wear masks in all indoor company settings.

Delta stopped short of matching United Airlines, which will require employees to be vaccinated starting Sept. 27 or face termination. However, the $200 monthly surcharge, which starts in November, may have the same effect.

“This surcharge will be necessary to address the financial risk the decision to not vaccinate is creating for our company,” Bastian said in a memo to employees.

Delta is self-insured and sets premiums for its plans, which are administered by UnitedHealthcare.

Bastian said that 75% of Delta employees are vaccinated, up from 72% in mid-July. He said the aggressiveness of the leading strain of the virus “means we need to get many more of our people vaccinated, and as close to 100% as possible.”

“I know some of you may be taking a wait-and-see approach or waiting for full (Food and Drug Administration) approval,” he told employees. “With this week’s announcement that the FDA has granted full approval for the Pfizer vaccine, the time for you to get vaccinated is now.”

A growing number of companies including Chevron Corp. and drugstore chain CVS announced they will require workers to get vaccinated after Monday’s FDA decision.

United and Delta already require new hires to be vaccinated. Two smaller carriers, Hawaiian and Frontier, have said they will require either vaccination or regular testing for current employees. Other major U.S. airlines, including American and Southwest, said today that they are encouraging employees to get vaccinated but have not required it.

Delta’s requirement for weekly testing of unvaccinated employees will start Sept. 12, and the requirement that the unvaccinated wear masks indoors takes effect immediately.

Fueled by the now-dominant delta variant of the virus, new reported cases of COVID-19 in the U.S. have topped 150,000 a day, the highest level since late January. Nationally the rate of increase has slowed, but the variant threatens to overwhelm emergency rooms in parts of the country.

On Tuesday, Gov. Brian Kemp of Georgia, where Delta is based, ordered members of the National Guard to 20 hospitals across the state to help deal with a surge that is larger than the national average.

Southwest, Spirit and Frontier have blamed the rise of the delta variant for a slowdown in customers booking flights, and U.S. air travel remains down more than 20% from pre-pandemic 2019.

The Delta CEO referred to the COVID-19 mutation that originated in India by its medical name, B.1.617.2, rather than the more common term, the delta variant.