TORONTO — Two new reports are painting differing pictures about the risk of air travel amid the COVID-19 pandemic.
A new study from Harvard University suggests that flying during the pandemic is less risky than eating at restaurants or going grocery shopping. However, a contrasting report about a COVID-19 outbreak linked to a seven-hour flight to Ireland is raising renewed concerns about in-flight transmission.
Researchers with the Aviation Public Health Initiative (APHI) at Harvard reported that air travel “is as safe as or substantially safer than the routine activities people undertake during these times.”
The study, released Tuesday, says current safety measures including ventilation, increased disinfecting, face mask enforcement and physical distancing during boarding and deplaning has significantly reduced the risk of contracting the novel coronavirus while flying.
“With comprehensive adherence to these preventive measures by airlines and passengers, air travel, along with other sectors of society, can responsibly return to some level of normal activity as we await development of an effective vaccine,” Leonard Marcus, Co-Director of APHI, said in a press release.
The study, which was sponsored by various airline operators, manufacturers and airports in the U.S., says the ventilation system in the plane’s cabin “effectively counters the proximity travellers are subject to during flights.”
Because of the frequent exchange of air and HEPA filters on planes, the study says “over 99 per cent of the particles containing the virus are removed from cabin air,” bringing the risk of COVID-19 transmission to below that at stores and restaurants.
However, the researchers acknowledged that airlines can make improvements to better protect passengers and crew by increasing physical distancing and keeping the airplane’s ventilation systems on when the plane is parked at the gate. The study noted these practices are not in place for all U.S. air carriers.
Despite these findings, a new report from the Irish Department of Public Health suggests COVID-19 transmission on airplanes remains a threat.
The report, published Thursday in the European medical journal Eurosurveillance, found that 13 of 49 passengers on a seven and a half hour flight to Dublin over the summer tested positive for COVID-19, and another 46 in contact with them in Ireland later became infected.
The report did not note the airline or where the flight originated, only that the travellers had flown to Europe from three different continents and transferred through a large, international airport.
Researchers say the outbreak “demonstrates the potential for spread of SARS-CoV-2 linked to air travel” and is one of few studies thus far to demonstrate in-flight transmission of the virus that causes COVID-19 with “extensive onwards transmission.”
Of the 13 passengers who tested positive after the flight, 12 were symptomatic, according to the study. Researchers noted that four people who contracted the virus from the flight were hospitalized and one was admitted to the ICU. One child was also infected.
The first of the cases was detected after a couple passengers developed symptoms two days after landing in Ireland, while the latest case in the outbreak occurred 17 days after the flight.
The study said only 49 of the aircraft’s 283 seats were filled during the flight, which is approximately 17 per cent of its capacity. Most of the passengers had been travelling together in small groups, but they were seated in different areas of the plane.
“Four of the flight cases were not seated next to any other positive case, had no contact in the transit lounge, wore face masks in-flight and would not be deemed close contacts under current guidance from the European Centre for Disease Prevention and Control,” the study said.
In addition to public health measures such as wearing a face mask and physical distancing, researchers stressed that “rapid contact tracing” done in conjunction with health authorities and airlines, is necessary to help limit onward spread of the virus when travelling.
The study noted that 11 of the flight’s passengers could not be contacted and were consequently not tested.
“Stringent on-board infection prevention and control measures are vital to reduce the risk of both symptomatic and asymptomatic in-flight transmission,” the study said.