Two small studies conducted in the early stages of the pandemic found a direct link between traveling on a long flight where masks weren’t required and testing positive for COVID-19.
But one significant caveat is that the studies didn’t measure the effects of wearing masks on planes, because they were conducted before major airlines introduced mask mandates.
Additionally, since the studies were conducted in March, many airlines including JetBlue JBLU,
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Is coronavirus airborne?
Initially, the U.S. Centers for Disease Control and Prevention said that the main way coronavirus spreads is via respiratory droplets that can infect someone who is within six feet of a person who has contracted the virus.
But the CDC recently altered its guidance to indicate that the virus can spread through the air and therefore could be contracted by inhaling virus-containing air particles. Those are formed “when a person who has COVID-19 coughs, sneezes, sings, talks, or breathes,” the agency stated.
The agency abruptly removed that language from its site on Monday, stating that it had been “posted in error to the agency’s official website.”
“CDC is currently updating its recommendations regarding airborne transmission of SARS-CoV-2 (the virus that causes COVID-19),” the CDC website stated as of Monday afternoon.
(The agency did not directly respond to MarketWatch’s request for comment.)
That wouldn’t be the first time the agency reversed course in a noteworthy manner during the pandemic.
In March, CDC officials said the general public shouldn’t wear masks; it later reversed course. And just weeks ago, the agency walked back its recommendation that asymptomatic individuals who have come in contact with someone who has tested positive for the virus don’t need to get tested.
The CDC has maintained throughout the pandemic that traveling increases your chances of “getting and spreading COVID-19,” and that “staying home is the best way to protect yourself and others from COVID-19,” the CDC states on its site.
Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases for three decades, told MarketWatch in a July interview that he wouldn’t be getting on a plane anytime soon, given that, at 79 years old, he is “in a risk category”
However the CDC says on its website that the novel coronavirus and other viruses “do not spread easily on flights because of how air circulates and is filtered on airplanes.” But flying remains a concern because “social distancing is difficult on crowded flights, and sitting within 6 feet of others, sometimes for hours, may increase your risk of getting COVID-19.”
What the new studies showed
One study traced four cases of the coronavirus-borne disease COVID-19 to a 15-hour flight from Boston to Hong Kong on March 9. Two passengers were a married couple who were hospitalized on March 15 after testing positive for the virus. The other two cases were flight attendants, one of whom served the couple during the flight.
Genetic analysis of virus specimens from the four people uncovered a “100% identical” genetic sequence, wrote an international group of researchers from the London School of Hygiene & Tropical Medicine and the University of Hong Kong and other institutions, in a peer-reviewed study in Emerging Infectious Diseases, a journal published by the CDC.
“ ‘Although we cannot completely rule out the possibility that patients C and D were infected before boarding, the unique virus sequence and 100% identity across the whole virus genome from the 4 patients makes this scenario highly unlikely’ ”
The researchers concluded that the married couple likely contracted the virus in North America before boarding the plane and transmitted it to the flight attendants (referred to as patient C and D in the study).
“Although we cannot completely rule out the possibility that patients C and D were infected before boarding, the unique virus sequence and 100% identity across the whole virus genome from the 4 patients makes this scenario highly unlikely,” the researchers wrote. “We therefore conclude that these 4 patients belong to the same in-flight transmission chain.”
No other cases of coronavirus associated with that specific flight were identified, according to the study. Additionally, the researchers were “unable to quantify the virus attack rate on this flight because not all passengers were tested.”
A second study, also published in the November edition of Emerging Infectious Diseases, traced 12 cases to one 10-hour flight on March 2 from London to Hanoi, Vietnam. In total 217 people, including passengers and crew, were on the flight.
The 12 people who tested positive for the virus were seated in business class, where the only symptomatic passenger on the flight was also seated, according to researchers from Vietnam and Australia, the majority of whom are affiliated with the National Institute of Hygiene and Epidemiology in Hanoi.
“ Since all 12 of these passengers were departing directly from the United Kingdom at a time when the country only reported 23 confirmed coronavirus cases, the authors conclude that it is most likely the case that they contracted the virus on the flight ”
Unlike the prior study, this one did not perform a genetic analysis to confirm identical virus sequences that would verify whether the 12 passengers likely contracted the virus from the symptomatic passenger on the flight.
However, because all 12 of these passengers departed directly from the United Kingdom at a time when the country had only 23 confirmed coronavirus cases, the authors concluded that it is most likely the case that they contracted the virus on the flight.
“ ‘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’ ”
“Although testing had not been implemented on a large scale nationwide at that time, community transmission in the United Kingdom was not yet widely established, making the presence of multiple persons on board incubating the illness unlikely,” the researchers wrote.
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“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,” they concluded. “As long as COVID-19 presents a global pandemic threat in the absence of a good point-of-care test, better on-board infection prevention measures and arrival screening procedures are needed to make flying safe.”
As of Monday, COVID-19, the disease caused by the virus SARS-CoV-2, had infected 31.2 million people globally and 6.8 million in the U.S. It had killed nearly 1 million people worldwide and at least 200,000 in the U.S., according to Johns Hopkins University.