Two passengers on an international commercial flight may have contracted COVID-19 on the airplane, researchers from Germany found.
A flight of 102 people from Tel Aviv to Frankfurt apparently included seven infected individuals (“index cases”). Two others believed not to be infected when they boarded were later diagnosed with the infection, reported Sandra Ciesek, MD, of Goethe University Frankfurt am Main, and colleagues.
Both sat within two rows of index cases, Ciesek’s group wrote in a JAMA Network Open research letter. The authors noted, however, that they couldn’t prove the two passengers contracted their infections on the plane.
One factor that may increase the chance of mid-air transmission: passengers were not wearing masks.
Little research exists about the extent of SARS-CoV-2 transmission on an airplane, though the U.S. recently lifted its global advisory against international travel.
Ciesek and colleagues reviewed the 4-hour, 40-minute flight from Tel Aviv to Frankfurt on March 9. Among the passengers was a tourist group. Beginning 7 days earlier, the group had contact with a hotel manager who was later diagnosed with COVID-19, but no member of the group was diagnosed with the virus prior to the flight.
That changed when the plane landed in Germany, however. Of the 24 members in the tourist group, seven tested positive for SARS-CoV-2 via a throat swab on arrival. Four passengers were symptomatic during the flight, two were pre-symptomatic, and one was asymptomatic.
They also were able to interview 71 of 78 other passengers 4 to 5 weeks later. Passengers within two rows of the index case and those who reported symptoms were offered an antibody test. Borderline or positive IgG tests were confirmed with a plaque reduction neutralization test (PRNT).
Serum samples from 13 of these passengers were obtained about 6 to 9 weeks following the flight. Of these, one passenger tested positive for SARS-CoV-2 4 days after the flight, but could not recall any symptoms, and SARS-CoV-2 IgG was detected 7 weeks after the flight, with a positive PRNT result.
Seven other passengers said they were symptomatic within 14 days after the flight. One passenger reported “headache, muscle ache and hoarseness” beginning 5 days after the flight. Nine weeks later, researchers got a serum sample and SARS-CoV-2 IgG was detected, though the PRNT result was borderline.
However, the six other symptomatic and five other asymptomatic passengers who provided serum samples 9 weeks after the flight tested negative except for one, who had a borderline result on the IgG, but a negative result on PRNT.
SARS-CoV-2 transmission could not be excluded for one passenger who had previous contact with a COVID-19 patient, and the 46 asymptomatic passengers who were not tested.
Ciesek and colleagues cited prior research noting both SARS and influenza transmission may occur among passengers seated beyond the “two-row perimeter.”
They noted the airflow in the cabin “from the ceiling to the floor and from the front to the rear” may be tied to a reduced rate of transmission, but with a caveat: “Our findings do not rule out airborne transmission of SARS-CoV-2 in an airplane cabin,” they wrote.
Disclosures
The authors disclosed no relevant relationships with industry.
Primary Source
JAMA Network Open
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