While airlines tout on-board mask mandates and pre-flight symptom checks, it's still easy for people with COVID-19 to get on a plane.
In a review by 51˶ of policies from six major U.S. airlines, all mandate masks while on board. These can be taken off to eat and drink, and in most cases children under 2 aren't required to wear them.
Most of the airlines also require passengers to confirm at check-in that they haven't had COVID-19 symptoms in the previous 14 days.
But there are no objective checks such as pre-flight temperature readings, and a confirmed negative test isn't required to board a flight for any of the six carriers: United, Delta, American, Southwest, JetBlue, and Alaska.
While temperature/symptom checks and testing certainly aren't perfect -- indeed, the CDC recently concluded that , catching only one case for every 85,000 travelers screened, prompting the federal government to -- U.S. airline policies largely rely on an honor system for keeping COVID out of their cabins.
strongly discourage travel of any kind: "Staying home is the best way to protect yourself and others from COVID-19," according to the guidance, which also warns, "Don't travel if you are sick or test positive for COVID-19."
Earlier this month, and charged with reckless endangerment in Hawaii when they boarded a flight from San Francisco after knowingly testing positive. But that may be the only such case.
Meanwhile, reports have emerged -- one , one -- of people dying in flight from COVID-19 complications.
"The guidance cannot be clearer that people who have symptoms suggesting they could have coronavirus, and particularly if they've been confirmed positive for COVID-19, should not be flying," said Leana Wen, MD, of George Washington University. "But at the end of the day, we rely on people to self-report."
In July, a 38-year-old woman died on a Spirit Airlines flight from Las Vegas to Dallas that was diverted to Albuquerque for her medical emergency. She had asthma and was obese, .
Months later, in October, Dallas County confirmed the death and its cause. County Judge Clay Jenkins told a local NBC affiliate that it "became difficult for her to breathe, and they tried to give her oxygen. It was not successful, and she died on the jetway."
This week, two passengers (see and ) on board United Airlines flight UA591 tweeted that a man with COVID-19 died during their Dec. 14 flight from Orlando to Los Angeles, which was diverted to New Orleans for his medical emergency. While local officials have not confirmed the death was due to COVID-19, both passengers said the man's wife had told first responders her husband had been having symptoms of COVID-19.
Pulmonology, infectious diseases, and critical care physicians contacted by 51˶ said it's plausible that these patients could have died from COVID-19 complications in flight.
The deaths could have been due to cardiomyopathy induced by the virus, which could have triggered a life-threatening arrhythmia. They could also be due to pulmonary embolism, given that patients with COVID-19 are frequently in a hypercoagulable state and flying is already known to be associated with deep vein thrombosis.
It's probably not due to the sometimes-rapid decompensation seen in hospitalized patients, said Suraj Saggar, DO, chief of infectious diseases at Holy Name Medical Center in Teaneck, New Jersey.
"Someone at that stage likely wouldn't be able to get on a plane," he said.
But experts did note that oxygen levels could be affected by cabin pressurization, which usually falls to the equivalent of an altitude of 6,000 to 9,000 feet. That could have an impact on someone who was short of breath before boarding.
Hooman Poor, MD, a critical care and pulmonology physician at Mount Sinai Hospital in New York City, cautioned that any arrhythmia or pulmonary embolism still could have occurred mid-flight, regardless of a COVID-19 diagnosis.
"It's clear COVID increases the risk of blood clots and so on, but it's difficult to say what led to what," Poor cautioned.
Some airlines are rolling out pre-flight testing for select routes, usually to help passengers get out of an extended quarantine requirement in the places that they travel to, such as New York.
American Airlines recently began offering to such passengers, and United Airlines expanded its pre-flight rapid testing for to those . Those who don't get tested will be switched to other flights to guarantee everyone on board tested negative before departure, .
Experts acknowledged that it's not feasible to test every airline passenger before they board given the country's limited testing supplies. Still, concerns about air travel extend far beyond in-flight risk.
"I'm most concerned about what happens when people get to their destination, when they socialize in poorly ventilated spaces, when they travel to virus hot spots," Wen said. "I really urge people to reconsider their travel plans."