Air filters in the jet alone cannot prevent infection

Air filters in aircraft can certainly reduce coronavirus infections, but cannot completely eliminate the risk. According to a Frankfurt study, wearing the mask definitely makes sense.

It makes sense: a mask on the plane, here worn by a Eurowings stewardess

IDespite the air exchange and filter systems, the new coronavirus may be transmitted in aircraft if the passengers do not wear mouth and nose protection. This is the result of an investigation by the Frankfurt University Hospital into the risk of infection in commercial aircraft. At the same time, the authors of the study conclude from the results that the filter systems in aircraft reduce the risk of transmission. However, infection cannot be ruled out – especially if no masks are worn.

This was exactly the case with the flight examined in the study: The 102 people examined had flown from Tel Aviv to Frankfurt in an ordinary passenger plane at the beginning of March. At that time, there were no special rules to protect against infection with the coronavirus, such as a mask requirement. Some of the passengers belonged to a group that was known to have had risk contact prior to departure. After arriving in Frankfurt, the members of the tour group were tested. In seven of the 24 group members, the Sars-CoV-2 test was positive immediately after the flight, so they were already infected on the plane.

Which cannot be ruled out

Sars-CoV-2 was later also detected in two passengers who did not belong to the travel group. Because of the chronological sequence and because these two passengers stated in surveys that they had not had any risky contacts either before the flight or afterwards, the authors of the study assume that the two of them were infected on the plane.

Although it cannot be ruled out with absolute certainty that the two infected people were infected at the airport at the gate or on some other occasion, all the information available suggests that the infection took place on the plane, especially since both were close to the previously infected people Sebastian Hoehl, doctor at the Institute for Medical Virology at the University Hospital and first author of the study, explains.

Infection despite the filter system

Despite certain ambiguities, according to the authors, conclusions can be drawn from the study for the safety of flying under the conditions of the corona pandemic. It was very likely that individual transmissions occurred in the aircraft in question despite the ventilation and filter system. However, the transmissions probably only happened in the immediate vicinity of the previously infected people.

The authors consider the fact that only two passengers were infected, even though seven were infected on the plane, as an indication that the air filter systems in the plane reduce the transmission of the virus – even if they cannot completely eliminate the risk. In any case, it can be deduced from the investigation that additional precautions in the aircraft, especially wearing mouth and nose protection, are “very useful”, the statement from the university hospital said.

In addition to the University Hospital and Goethe University, the city health department was involved in the study.