Almost 10,000 people tested negative before flying. Only one was positive after landing, according to a study.

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A study of Delta Air Lines passengers to Italy found that a mandatory PCR coronavirus test performed within three days of the flight eliminated the vast majority of travelers infected with the virus.

The study looked at data from the airline’s program that allowed travelers to bypass quarantine in Italy if they provided evidence of a negative molecular test within 72 hours and got a rapid test at the airport. ‘Atlanta or New York before departure. The passengers had to undergo another quick test after landing in Italy.

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The study was conducted by the Mayo Clinic, Delta Air Lines, and the Georgia Department of Health. The article, which was published earlier this month, will appear in the journal Mayo Clinic Proceedings.

Of 9,853 travelers who tested negative for coronavirus within 72 hours of departure, 0.05% – or five people – were found to have an active infection immediately before or after the flight. The flights took place between December 2020 and May 2021; the study indicates that the average prevalence rate of infection in the community was estimated at 1.1 percent during this period.

Four of those five passengers were discovered by rapid antigen tests, which were confirmed by rapid molecular tests, before boarding at the airport. They were not allowed to steal.

This left a passenger who did not test positive before arriving in Italy.

“These data suggest that even at this higher level of active community infection, a single molecular test performed within 72 hours of departure can reduce the rate of active infection on board a commercial aircraft to levels of several orders.” less than active community infection. rate, ”says the study. “The addition of other interventions, including universal masking at the airport and on board aircraft, increasing the frequency of air exchanges and improving customs clearance, physical distancing during disembarkation activities , increasing vaccination rates among travelers and excluding symptomatic people further improves safety. “

Delta said it was covering the test costs associated with the flights but had no funding role in the study. Mayo Clinic worked with Delta to design the testing program under a long-standing partnership.

In an article on its news page, Delta said the results showed “the feasibility of implementing a test protocol with significant impact.”

“We’re going to be living with variants of covid-19 for a while,” Henry Ting, the airline’s health director, said in the article. “This real-world data – not simulation models – is what governments around the world can use as a model to require vaccinations and tests instead of quarantines to reopen borders for international travel.”

Many international destinations require testing before passengers leave, sometimes in addition to vaccination. But with the exception of flights to Hawaii, there is no mandate for testing before domestic flights.

“If you are in a confined space for more than six hours as an international flight implies, it will inherently present more risk than a one hour domestic flight,” said lead author Aaron Tande, medical specialist. infectious diseases at the Mayo Clinic. in Rochester, Minn. He said there are broader discussions to be had as to whether testing is needed for all flights as opposed to those that carry a higher risk.

The study was conducted before the highly contagious delta variant became dominant in the United States and included many months during which vaccines were not available to the general population.

Tande said the absolute research numbers could differ if it were to repeat itself now, with the delta variant in play, more people vaccinated and a different level of community infection. Still, he said, the results show that the tests would reduce the risk of infection on an airplane.

Tande said it was always clear that air travel needed “multiple layers of mitigation.” He said most cases of transmission reported during flights have occurred either before masking was universal or when there were failures in wearing the mask, which can include eating and drinking.

“To me it’s very clear that you should have universal masking on flights,” he said. “And then testing is another layer to reduce risk.”

He said his ideal safe flight would go one step further: everyone on board would be vaccinated, tested and masked.

“Do I want to be on a vaccinated flight? ” he said. “100 per cent.”

The study recognizes “significant limitations,” including the possibility that those who flew were more likely to consider themselves at low risk of contracting the virus, or that exposed travelers may have decided to stay home because they knew that they would be tested.

“This possibility may limit the generalization of our conclusions and recommendations to the general population of commercial air travelers,” the study said.

Rapid antigenic tests, which are less sensitive than molecular tests, could also have produced false negatives and allowed those infected to be tested. Tande said the study did not follow those 9,800-plus passengers to find out whether any of them – including those on the flight with the person who tested positive – had been infected.

The article says the results show a “low yield” of additional rapid testing at the airport after a negative PCR test. According to the study, this suggests that “this additional test is unlikely to add safety to other mitigation efforts (i.e. masking), especially as vaccination rates increase rapidly. “.