Pre-flight testing shows decrease in COVID-19 infections on board

Real-world data from nearly 10,000 air travellers has provided a reliable pre-flight testing blueprint as more countries consider travel requirements.

The risk of exposure to COVID-19 while travelling after all passengers test negative 72 hours in advance of a flight is less than 0.1 percent. This is according to a unique study that examined real-world customer data on Delta’s COVID-tested flight corridors between New York-JFK, Atlanta and Italy’s Fiumicino International Airport.

The peer-reviewed study published in Mayo Clinic Proceedings showed a single COVID-19 molecular test performed within 72 hours of departure could decrease the rate of people actively infected onboard a commercial aircraft to a level that is significantly below active community infection rates.

For example, when the average community infection rate was at 1.1 percent, infection rates on COVID-19-tested flights were 0.05 percent. The Georgia Department of Health and Mayo Clinic conducted the study in conjunction with Delta.

“We are going to live with COVID-19 variants for some time. This real-world data – not simulation models – is what governments around the world can use as a blueprint for requiring vaccinations and testing instead of quarantines to re-open borders for international travel,” Henry Ting, Delta’s Chief Health Officer explained.

“Air travel risk varies depending on case rates and vaccination rates at the origin and destination, masking and other factors. But the data collected from this study show that the routine use of a single molecular test within 72 hours before international travel for unvaccinated individuals significantly mitigates the risk of COVID-19 exposure and transmission during airline travel.”

Ting added that our real-world experience and testing protocol demonstrate that a very low risk of infection transmission is possible, confirming previous simulation models of viral transmission on planes.

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The study began in December 2020 with the trans-Atlantic COVID-19 testing program that enabled quarantine-free entry into Italy and allowed teams to review and model various testing strategies for feasibility, false-positive rates and case detection rates.

Now, the results of this study are available – offering unique data insights on the risk of SARS-CoV-2 exposure, infection rates on board and showing the feasibility of putting in place a testing protocol with meaningful impact.

“When you couple the extremely low infection rate on board a COVID-19-tested flight with the layers of protection on board including mandatory masking and hospital-grade air filtration, the risk of transmission is less than one in one million between the United States and the United Kingdom, for example,” Ting added.

He said these numbers will improve further as vaccination rates increase and new cases decrease worldwide.

Among the 9,853 potential passengers who underwent testing in the U.S., 4 (0.04 percent) individuals tested positive by both the rapid antigen and confirmatory molecular tests.

During the study period, the average community infection prevalence rate was estimated at 1.1 percent.

Individuals who tested positive by both the rapid antigen and confirmatory molecular tests were considered true positives and were not allowed to board. There were no false-positive rapid antigen tests.

The estimated risk of a false-negative antigen test is 0.00009.

A single molecular test performed within 72 hours of departure can decrease the rate of active infection onboard a commercial aircraft to a level that is several orders of magnitude below active community infection rates.

A low yield of additional rapid antigen testing at the airport suggests that further testing is unlikely to add safety alongside other mitigation efforts (i.e., masking), especially as vaccination rates are rapidly increasing.

During a period of high COVID-19 infection burden within the U.S., a single molecular test performed within 72 hours of departure led to a low percentage of airline passengers identified with the virus on rapid antigen testing during travel. This data may inform future recommendations for testing during travel and eliminate the need for quarantine after travel.