A group of 239 scientists from 32 countries are urging the World Health Organization (WHO) to review its guidance on the airborne spread of the novel coronavirus as case numbers rise around the world.
In a forthcoming paper titled “It is Time to Address Airborne Transmission of Covid-19,” 239 signatories attempt to raise awareness about what they say is growing evidence that the virus can spread indoors through aerosols that linger in the air and can be infectious even in smaller quantities than previously thought.
Until recently, most public health guidelines have focused on social distancing measures, regular hand-washing and precautions to avoid droplets. But the scientists say the potential of the virus to spread via airborne transmission has not been fully appreciated even by public health institutions such as the WHO.
“There is no reason for fear. It is not like the virus has changed. We think it has been transmitted this way all along,” said Jose Jimenez, a chemist at the University of Colorado who signed the paper. “Knowing about it helps target the measures to control the pandemic more accurately.”
The paper, which was shared with some media ahead of publication comes as the WHO faces criticism over its coronavirus response, calls for reform and a U.S. threat to cut funding and withdraw completely.
A spokesperson for WHO said it is aware of media reports about the issue and will have technical experts review the matter. The agency has repeatedly defended its handling of the pandemic.
Since the early days of the coronavirus crisis, the WHO and its director-general, Tedros Adhanom Ghebreyesus, have been dogged by questions about whether the agency’s effusive praise for China created a false sense of security and potentially spurred the spread of covid-19, the disease caused by the virus.
That criticism has been compounded at various points by questions about its positions on technical issues, including transmission, mask use — and, now, airborne transmission.
The signatories to the paper contend that the virus can still spread through aerosols, or tiny respiratory droplets, that infected people cough or otherwise release into the air. In crowded or poorly ventilated indoor settings, this could be especially dangerous, and would account for a number of “superspreading” incidents.
Co-author of the paper, Donald Milton, a professor of environmental health at the University of Maryland, said the WHO’s apparent reluctance to emphasize this aspect of the virus’s ability to spread is probably because of the difficulty identifying tiny infectious particles.
“It is easy to find virus on surfaces, on hands, in large drops,” he said in an emailed statement. “But, it is very hard to find much less culture virus from the air — it is a major technical challenge and naive investigators routinely fail to find it.
Jimenez said the scientists’ purpose was not to hurt the agency, but merely to encourage it to consider new information.
“Our group of scientists doesn’t want to do anything that would undermine the WHO as an organization,” he said. “We only want it to adapt its guidance on aerosol transmission to the increasing evidence.”
UPDATE: The World Health Organization has since revised its official guidelines on how the coronavirus is spread to reflect that airborne transmission of the virus “cannot be ruled out.”