By Shannon McMahon
This week, United Airlines announced a trial of flights between Newark Liberty International Airport in New Jersey and London Heathrow where every passenger receives a rapid coronavirus test before boarding.
The program runs until Dec. 11 and is part of "the airline's free transatlantic Covid-19 testing pilot program."
Rapid antigen testing technology displays results in minutes, unlike the more accurate polymerase chain reaction (PCR) tests now required by many destinations for entry. (The United Kingdom does not require Americans to get tested before arrival, but it does mandate a 14-day quarantine.)
The flights were touted as "Covid-free" in reports by Forbes, CNN and other travel sites.
But it's misleading to call something "Covid-free," especially a flight with only rapid antigen testing, said David Freedman, an infectious-disease specialist at the University of Alabama, who has reviewed studies on in-flight transmission.
This week, the Food and Drug Administration updated its guidance on the rapid-test technology, saying that rapid tests are intended for use on people showing Covid-19 symptoms and have a far lower accuracy rate than the preferred PCR tests.
"Rapid tests are under emergency use authorization, and so they have not gone through full FDA scrutiny ... most are 70 to 80 percent as sensitive as a PCR test," Freedman says. In other words, he stresses, "they miss about 20 to 30 percent of cases that a PCR would pick up."
Rapid antigen tests recently made headlines when SpaceX and Tesla CEO Elon Musk said he took four in one day, receiving split results of two positives and two negatives, before conceding he "most likely" has Covid-19.
While headlines dubbed the flights "Covid-free," airlines have not. United said in an email that "United has said this is the first of its kind transatlantic testing program which guarantees customers over two years old and crew test negative before departure." German airline Lufthansa, a partner with United, is trialling similar flights.
The term appears to have been attached to reports about rapid-tested flights since September, when Forbes covered Alitalia's coronavirus-tested flights.
Premise Health, which is providing the rapid-test service for United's Heathrow-Newark flights, says it is aiming to provide another layer of safety to passenger, and not a Covid-free environment, until a vaccine is available.
"No test is perfect, which is why we see testing as part of a layered approach that includes other safety measures to help prevent the spread of Covid-19, such as wearing masks," Premise Health President Jami Doucette said. "There are hundreds of antibody, PCR and antigen tests that have received emergency use authorization, and accuracy varies by specific test, not just the category of test."
United has been notifying all customers booking the route that they would be required to take a rapid test. "If someone didn't want to be tested, we then accommodated them on another flight or provided a refund," United spokesperson Robert Einhorn said in an email.
Freedman points out that even if PCR tests were given to everyone onboard, no flight can be guaranteed to be Covid-free. All coronavirus diagnostic tests can and do miss contagious passengers; rapid antigen tests are just more likely to miss them. And, he says, the risk of a coronavirus-infected individual being on your flight depends on the amount of cases that exist in the area at the time of travel.
"Right now, there's so much Covid out there that the chances of one Covid-positive person sneaking by and onto a flight, even if everyone is tested, is substantial," Freeman says.
"The airlines just want to do something to sway passengers that their particular plane is safer on that day."