A German study done by Institute for Medical Virology at Frankfurt’s Goethe University suggests that a properly safe air travel, observing some sort of social distancing by the passengers on board, may be in order once the panic of COVID-19 subsides and borders for air travel open because risks of transmission of virus are low.
The case study involved a commercial airline flight from Tel Aviv, Israel, to Frankfurt, Germany, that occurred on March 9th, 2020. Among 102 passengers on a Boeing 737-900 aircraft were 24 members of a tourist group. Starting 7 days earlier, the group had contact with a hotel manager who later received a diagnosis of coronavirus disease 2019 (COVID-19). No member of the group had received a diagnosis of COVID-19 before the flight, and no measures to prevent transmission (eg, wearing of masks) had been applied. The flight duration was 4 hours 40 minutes.
At the destination airport, a medical evaluation of the tourist group was conducted, including testing for severe acute respiratory syndrome coronavirus (SARS-CoV-2) in a throat swab specimen. Researchers contacted passengers 4 to 5 weeks later by phone and conducted structured interviews. Passengers were asked whether they had contact with a person with COVID-19. They were prompted to report symptoms and asked about previous testing for SARS-CoV-2. A semi-quantitative SARS-CoV-2 IgG antibody test (EUROIMMUN) was offered to all passengers who had been seated within 2 rows of the COVID-19 positive cases and to those who reported to have been symptomatic.
Of the 24 members of the tourist group, 7 tested positive for SARS-CoV-2 RNA in a throat swab sample on arrival. Four of the 7 were symptomatic during the flight, 2 were pre-symptomatic, and 1 remained asymptomatic.
A total of 71 of the other 78 passengers (91%) who had been exposed to the group on the flight completed the interview. One reported having tested positive by polymerase chain reaction 4 days after the flight. This passenger did not recall any symptoms.
Seven other passengers reported having had symptoms suggestive of COVID-19 within 14 days after the flight. One had a headache, muscle ache, and hoarseness starting 5 days after the flight. This passenger had not been tested and negated known contact with patients with COVID-19. The passenger was in quarantine for 14 days starting 1 day after the flight.
It has previously been observed for SARS and influenza that transmission may also occur among passengers seated beyond the 2-row perimeter, 2, 3 indicating possible airborne transmission.
“Our findings do not rule out airborne transmission of SARS-CoV-2 in an airplane cabin” the study authors wrote.
“This study had several limitations. We did not obtain information on the crew of the airplane and were not able to contact all passengers. We also did not obtain antibody tests from all passengers.
Additional transmissions may have occurred and remained undetected.”
Although the study results suggest – risk of transmission of virus while airborne, the authors do not claim the experiment as foolproof and fully conclusive because there were many limitations.