Two new studies on the spread of Covid-19 in airlines suggested that the virus can proliferate on long-haul airline flights.

The first study was conducted by Vietnam’s National Institute of Hygiene and Epidemiology (VNIHE) published in the November 2020 pre-print edition of the journal Emerging Infectious Diseases .

The second study was conducted by a team of scientists from a multi-national group of institutions, including the London School of Hygiene & Tropical Medicine, University of Hong Kong, and others.

According to the study by VNIHE, although the international flight industry has judged the risk for in-flight transmission to be very low, long flights, in particular, have become a matter of increasing concern as many countries have started lifting flight restrictions despite ongoing SARS-CoV-2 transmission.

For the study, researchers examined 217 passengers who took a 10-hour commercial Vietnam Airlines flight from London to Hanoi on March 2 this year.

The researchers traced people, including crew members and passengers, who had interacted with each other within two meters for over 15 minutes.

The researchers found that 16 people had coronavirus. Twelve of those (75 per cent) were passengers seated in business class along with “Case 1,” the only symptomatic person on board the flight. “Seating proximity was strongly associated with increased infection risk,” wrote the researchers.

The team concluded: “We conclude that the risk for on-board transmission of SARS-CoV-2 during long flights is real and has the potential to cause Covid-19 clusters of substantial size, even in business class–like settings with spacious seating arrangements well beyond the established distance used to define close contact on airplanes.”

Second study

For the second study, the researchers examined four passengers with SARS-CoV-2 who had travelled on the same 15-hour flight from Boston to Hong Kong on March 9, 2020.

The cohort comprised two passengers (A and B) and two cabin crew members (C and D), all of whom were asymptomatic at the time of the flight. However, they were tested positive 11 days later.

The researchers concluded in the study: “Given the case histories and sequencing results, the most likely sequence of events is that one or both of passengers A and B contracted SARS-CoV-2 in North America and transmitted the virus to flight attendants C and D during the flight. The only location where all four persons were in close proximity for an extended period was inside the airplane.”

“Our results strongly suggest the in-flight transmission of SARS-CoV-2. Our results demonstrate that SARS-CoV-2 can be transmitted on airplanes. To prevent transmission of the virus during travel, infection control measures must continue,” the researchers added.

Recently, the Washington Post reported that the Centers for Disease Control and Prevention (CDC) has found around 11,000 people who were exposed to the coronavirus on flights.

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