It expands on an effort that already had been underway for flights from the U.K., and places a significant responsibility for policing on the airline industry itself. Airlines will have the responsibility of confirming negative results, and will have to deny boarding to passengers if they don’t meet the criteria.
The announcement meets part of a request from the U.S. airline industry, which has lobbied for pre-flight testing as an alternative to quarantines or other restrictions on who can enter the country. It’s unclear whether the government is immediately planning to do away with those other restrictions.
Testing has been the travel industry’s best hope for reinvigorating international air travel, and the major U.S. airlines already offer pre-flight testing to help passengers comply with rules in place at their destination. And this week the U.S. airline industry trade group Airlines for America endorsed CDC’s proposal to require a negative Covid test for travelers seeking entry into the U.S.
The new requirement may help passengers feel better about flying, but it’s not a silver bullet for avoiding infections. A study published last week in the CDC’s Emerging Infectious Diseases journal warned that testing passengers for Covid-19 before they fly may not fully prevent in-flight spread of the virus.
Notably, the study came to its conclusions thanks to the kind of enforced quarantine program that the travel industry is fighting to avoid. The researchers studied seven Covid cases detected through New Zealand’s aggressive 14-day “managed isolation and quarantine” program.
Long haul flights are particularly vulnerable to potential in-flight transmission of the virus because it’s harder to avoid crowding and masks are difficult to keep on for the entire trip, according to Jeff Engel, senior adviser for Covid-19 at the Council of State and Territorial Epidemiologists.
“Airlines are always reporting that they circulate their air through filters that filter out 99.9 percent of germs, which is true,” Engel said. “But transmission occurs through direct person-to-person spread without that air even going through the circulation system.”
In addition, a test is only a snapshot in time. Justin Lessler, an associate professor of epidemiology at the Johns Hopkins Bloomberg School of Public Health, cautioned that if airlines only require a negative test that was taken a few days before passengers actually travel, individuals could become infectious in the time between the test and stepping onto their plane.
Testing passengers at the airport using antigen tests that deliver results at the point-of-care would “likely significantly cut down” on the risk of transmission, but Lessler warns there will “always be residual risk.”
“That would be far more effective than a PCR test two or three days before somebody got on the aircraft,” Lessler said. “I think that it would have a positive public health impact.”
In any case, the airport industry has opposed testing in airports. The Airports Council International warned last year that creating long lines for screening in airports would go against social distancing and create security risks.
Airlines have also raised concerns about the availability of testing to meet the demands of a requirement. In a recent letter to the Trump administration, the U.S. airline trade group asked the government to consider making rapid testing available to aid airlines in meeting the impending requirement.
The industry had also asked for a two-week implementation timeline, to train staff and alert customers.
The Department of Homeland Security, which would be responsible for lifting the existing restrictions on non-citizens entering the U.S. from Europe, the U.K., Brazil and elsewhere, did not respond to a request for comment.
Tanya Snyder contributed to this report.