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The proposal to require domestic airline passengers to prove they have tested negative for Covid-19 is a “horrible idea,” according to Delta Air Lines CEO Ed Bastian.

Bastian told CNN’s Poppy Harlow Tuesday that the proposal being discussed by the Biden Administration would drain testing resources away from people who need it more. He said the number of confirmed Covid cases transmitted during air travel since the start of the pandemic has been “absolutely minimal.”

“It will not keep domestic flyers safer,” he said. Planes have hospital quality air filters on board and exchange fresh air into the cabin every few minutes, reducing the chance of transmission.

“In fact [there are] very, very few documented cases globally, not just domestically,” Bastian said of air-travel related infections. He added that the domestic testing requirement would take “about 10%” of the resources the country needs “to test sick people away from those people.”

Covid tests are required for some international travelers in an effort to stop new variants of the virus from spreading more rapidly in the United States. Tests are also required before boarding flights to Hawaii but not for most domestic flights.

Bastian said adding the requirement would be a “logistical nightmare” that would be a body blow to the already struggling airline and hospitality industries.

“It would set us back another year in the recovery,” he predicted.

Transportation Secretary Pete Buttigieg told CNN that there is no decision yet to require testing, but it is one of the options being considered by the Centers for Disease Control.

“There has got to be common sense medicine and science really driving this,” he said.

Delta announced Monday that it would continue to not book passengers in its planes’ middle seats through at least April. It is the only US airline that continues to limit capacity.

“It’s expensive. No question about it,” Bastian said. But the cost of keeping the middle seat open is partly offset by higher fares that Delta has been able to charge, he added.

The amount that Delta passengers paid on average for every mile traveled in the final three months of the year was down only 3% from the pre-pandemic period a year earlier. That’s significantly better than that of the other three major US airlines – American (AAL), United (UAL) and Southwest (LUV) – which are battling declines of 15% to 19%.

“People are prioritizing, as they should, their health and safety and comfort as they travel,” Bastian said. “And we’re getting a meaningful premium for travel on Delta.”

Delta began offering vaccines to its employees at Atlanta’s Hartsfield Airport this week, prioritizing employees who are age 65 or older. The company is also offering vaccines to employees of other airlines.

Some have suggested vaccines should be required of all airline employees who interact with the public. But Bastian said it is too soon to discuss such a requirement.

“First of all, most of our employees can’t even get the vaccines. We don’t have the supplies yet,” he said. “We’ll strongly encourage vaccinations. I know our people understand how important it is to restore confidence back in travel and getting vaccinated is one of those steps that we’ll take. I think that’s a decision for later on as we go through the course of the vaccination efforts.”

Correction: A previous version of this story misspelled Delta CEO Ed Bastian's surname.