Why the WHO Took Two Years To Say COVID is Airborne

Early in the pandemic, the World Health Organization stated that SARS-CoV-2 was not transmitted through the air. That mistake and the prolonged process of correcting it sowed confusion and raises questions about what will happen in the next pandemic. Nature: According to Trish Greenhalgh, a primary-care health researcher at the University of Oxford, UK, the IPC GDG members were guided by their medical training and the dominant thinking in the medical field about how infectious respiratory diseases spread; this turned out to be flawed in the case of SARS-CoV-2 and could be inaccurate for other viruses as well. These biases led the group to discount relevant information -- from laboratory-based aerosol studies and outbreak reports, for instance. So the IPC GDG concluded that airborne transmission was rare or unlikely outside a small set of aerosol-generating medical procedures, such as inserting a breathing tube into a patient. That viewpoint is clear in a commentary by members of the IPC GDG, including Schwaber, Sobsey and Fisher, published in August 20202. The authors dismissed research using air-flow modelling, case reports describing possible airborne transmission and summaries of evidence for airborne transmission, labelling such reports "opinion pieces." Instead, they concluded that "SARS-CoV-2 is not spread by the airborne route to any significant extent." In effect, the group failed to look at the whole picture that was emerging, says Greenhalgh. "You've got to explain all the data, not just the data that you've picked to support your view," and the airborne hypothesis is the best fit for all the data available, she says. One example she cites is the propensity for the virus to transmit in 'superspreader events,' in which numerous individuals are infected at a single gathering, often by a single person. "Nothing explains some of these superspreader events except aerosol spread," says Greenhalgh. Throughout 2020, there was also mounting evidence that indoor spaces posed a much greater risk of infection than outdoor environments did. An analysis of reported outbreaks recorded up to the middle of August 2020 revealed that people were more than 18 times as likely to be infected indoors as outdoors3. If heavy droplets or dirty hands had been the main vehicles for transmitting the virus, such a strong discrepancy would not have been observed. Although the WHO played down the risk of airborne transmission, it did invite Li [a building environment engineer at the University of Hong Kong who suspected early on that SARS-CoV-2 was also airborne] to become a member of the IPC GDG after he spoke to the group in mid-2020. Had the organization not at least been open to his view that infections were caused by aerosols, especially at short range, "they would not have invited me there as they knew my standing," he says.

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