Quick Take:

Calls are rising for airlines to require vaccination proof for domestic passengers. Airlines aren’t happy about the idea.

To go into restaurants, visit gyms, go on a cruise or see the new “Spider-Man” movie in theaters, you need to show proof of vaccination in many parts of the country. But you don’t need proof of vaccination or a negative COVID-19 test to board a commercial flight within the U.S.

With coronavirus cases rising and airlines canceling thousands of flights due to outbreaks among staff, there is mounting pressure to change that.

Dr. Anthony Fauci, President Joe Biden’s top infectious disease advisor, told MSNBC news Monday that it would be “reasonable to consider” a vaccination requirement for domestic airline passengers. He did not say whether he had made this recommendation to Biden.

“When you make vaccination a requirement, that’s another incentive to get more people vaccinated,” Fauci said. “If you want to do that with domestic flights, I think that’s something that seriously should be considered.”

Sen. Dianne Feinstein and Reps. Don Beyer, Eric Swalwell and Ritchie Torres went a step further last week, asking that the Biden administration require proof of COVID-19 vaccination or a negative COVID-19 test result for all domestic air travel.

“Travel at our nation’s airports has essentially returned to pre-pandemic levels but the risk from COVID-19, including from its new variant Omicron, continues to present a major public health threat,” the members said in a statement. “Requiring proof of vaccination or a negative test for domestic flights would improve public health and address concerns that passengers have about flying.”

In November, 36 members of Congress, including Feinstein, signed a letter to Biden asking that he require such proof or a negative test results for all domestic flights as well as updated safety protocols for trains and other modes of travel.

“This is a necessary and long overdue step toward ensuring all Americans feel safe and confident while traveling and reduce the chances of yet another devastating winter surge,” the members of congress said in the letter.

The Biden administration on Nov. 8 began requiring inbound travelers to the U.S. to show proof of a negative COVID-19 test result, which several airlines were able to accomplish by requiring passengers to upload the information electronically through their boarding apps.

But Biden told ABC News last week that although vaccine requirements for domestic air travel has been considered, “the recommendation I’ve gotten is [that they are] not necessary.”

Despite COVID-19 outbreaks forcing the cancellation thousands of flights over the holiday travel season because of cases among airline employees, the industry appears set against vaccine requirements for domestic travel.

Airlines for America, a trade group that represents the nation’s airlines, agrees with Biden that the requirement is not needed. A spokesperson for the group declined to elaborate.

“We have been informed by the administration that there is no imminent policy proposal regarding a domestic travel requirement and echo concerns expressed by the administration about the implementation and enforcement of such a policy,” the group said in a statement.

Industry experts say airlines have logistical and financial reasons to oppose vaccination requirements for domestic flights.

Airlines are worried about having to process and verify hundreds of thousands of vaccination records and spot any fraudulent ones, said Henry Harteveldt, a travel industry analyst with Atmosphere Research Group.

“To have to show those documents to the airlines or the TSA security at airports will slow down the check-in process or security screening,” he said.

A study conducted by Atmosphere Research Group found that 14% of airline passengers were not vaccinated, which means they would be unable to fly if vaccination proof were required, Harteveldt said. Such a reduction would hurt airlines financially at a time when they trying to rebound from their worst financial crisis since the Sept. 11, 2001, terrorists attacks, he said.

That’s assuming a vaccination requirement would not allow an exemption for those who provide a recent negative COVID-19 test. Those who arrive in the U.S. on international flights must show proof of a negative test result taken within a day of departure.

Airline executives have also spoken out against the requirement that passengers wear masks on planes, a mandate that the Transportation Security Administration has extended through March 18, 2022.

Southwest Airlines Chief Executive Gary Kelly told a Senate committee last month that he thinks masks “don’t add much, if anything, in the air cabin environment.”

He suggested that the HEPA air filtration systems in commercial aircraft make the cabins safe against the spread of the virus. Studies have shown that HEPA filters on planes help reduce the risk of getting infected but do not eliminate the chances of contracting the virus entirely.

This story originally appeared in Los Angeles Times.