More than 200 scientists and experts around the world wrote an open letter to public health agencies, including the World Health Organization, on Monday, arguing that there is significant evidence that the new coronavirus can persist in the air and spread from person to person through particles in the air,media CNET reported. The letter, published Monday in the journal Clinical Infectious Diseases, advocates “preventive measures to reduce this route of air transmission, ” and was signed by 239 researchers from 32 countries.
The New York Times and the Los Angeles Times first reported on the existence of the open letter on Saturday, describing WHO as an organization “out of touch with science” on the matter.
“For SARS-CoV-2, air borne is sometimes possible, even possible.” Babak Javid, an infectious disease doctor at Tsinghua University School of Medicine, said in a statement. “There is no idea how common this is.”
WHO’s official guidance on this is that the virus is transmitted from person to person through “small droplets” that are excreted when patients with COVID-19 cough, sneeze or speak. These droplets are too heavy to spread over long distances and will sink quickly to the ground. In addition, the organization noted that the virus could be picked up from the surface. That’s why washing hands and keeping a social distance are important to help curb transmission.
But the signatories of the open letter argue that SARS-CoV-2 lingers in the air, which may play a role in spreading. They believe that when COVID-19 patients excrete the virus, the virus particles remain in the air and can travel far with the air flow, especially in poorly ventilated areas. “It is understood that there is no general acceptance of air transmission of SARS-CoV2, but there is sufficient supporting evidence in our collective assessment that the precautionary principle should apply,” they wrote. “
In order to reduce the risk of airborne transmission, they suggested that two main measures should be implemented. Improve ventilation in public buildings and reduce overcrowding. The report also calls on WHO to recognize this potential route of transmission and communicate the risks associated with it more effectively.
“We are concerned that a lack of awareness of the risks of air borne-insance in COVID-19 and the lack of clear recommendations on control measures for airborne viruses will have significant consequences,” the researchers wrote. “WHO has been reluctant to provide more recommendations to highlight risks, citing a lack of evidence.
Some scientists expressed concern about the letter, arguing that concerns about airborne transmission may be overstated. “I’m a little shocked by the problem,” said Isaac Bogoch, an infectious disease researcher at the University of Toronto. “There’s no new data, just a signed letter that’s headlined.”
The debate is over the interpretation of the mode of transmission, and the confusion extends to public awareness of how the disease is transmitted. “One of the problems here is a potential conflict between the technical concept of airborne transmission and the general public’s perception of the term,” says Jose Vazquez-Boland, chair of infectious diseases at the University of Edinburgh.
The academic debate is dominated by the confrontation of “droplets” — heavy particles that fall within six feet of the ground — against “aerosols” — light viral particles suspended in the air. The key difference is the size of the particles.
“The size of the droplets will be very important because all the things that effectively have mass or weight, ” explains Bruce Thompson, a respiratory specialist at the University of Swimburn in Australia. Larger droplets of respiratory tracts like sneezing don’t stay in the air for long; they fly in the air, but because of gravity, they quickly fall to the ground. Aerosols are different.
“If it’s an aerosol, it’s likely to float in the air for longer,” Thompson said. These technical distinctions make it difficult for the general public to understand what the virus means to “airborne.” It can be difficult for the public to distinguish between situations and technical definitions,” Vazquez-Boland said.
“There’s a bit of a dichotomy between droplets and airborne transmission,” Bogoch said. “It’s more like a spectrum. COVID-19 IS CLOSER TO THE DROP END OF THE SPECTRUM,” BOGOCH SAID.
Even if WHO underestimates the risks, it may not have a dramatic impact on combating transmission. As part of its official guidelines, the organization does recommend avoiding crowded places and protecting themselves from COVID-19. It also advises those who feel uncomfortable to stay at home or wear masks when they go out.