The coronavirus is finding clusters of new bodies to infect in indoor spaces like bars, restaurants, offices and casinos, increasingly pointing to viral particles lingering in the air and infecting those nearby.
The World Health Organization has long maintained that the virus is spread mainly by large droplets expelled from coughs and sneezes that fall relatively quickly to the floor.
But in an open letter to the W.H.O., 239 scientists in 32 countries have outlined the evidence showing that smaller particles can infect people, and are calling for the agency to revise its recommendations. The researchers plan to publish their letter in a scientific journal next week.
Even in its latest update on June 29, the WHO states that airborne transmission is only possible after medical procedures that produce aerosols, which means droplets of smaller than 5 microns. Therefore, according to the WHO, N95 masks and proper ventilation are only of concern in those circumstances. Instead the WHO has heavily promoted handwashing as the primary prevention strategy, even though the CDC now says that surfaces are likely to play a minor role in transmission.
Dr. Benedetta Allegranzi, the W.H.O.’s technical lead on infection control, said the evidence for the virus spreading by air was unconvincing.
“Especially in the last couple of months, we have been stating several times that we consider airborne transmission as possible but certainly not supported by solid or even clear evidence,” she said. “There is a strong debate on this.”
While the WHO finds itself at odds with other experts on the subject of airborne transmission, they also maintain that asymptomatic transmission of the virus is rare. Experts suggest that the WHO should err on the side of precaution, assume the worst of the virus, apply common sense and recommend masking up.
A WHO consultant in southeast Asia worries about what this is doing for the agency’s credibility, recalling that WHO staffers in his country were the only ones to go without masks even after the government endorsed them.
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