Six months into a pandemic that has killed more than half a million people around the world, it seems it may be time to update what we know about how COVID-19 is transmitted. A group of 239 scientists will publish an open letter this week calling on the World Health Organization to take into account that airborne transmission is a significant factor in how COVID-19 spreads. The group says WHO is being too reluctant to update the official view on transmission that downplays the risk of airborne transmission. If the organization does update its view, the implications would be huge, and a major adjustment to existing efforts to contain the virus would be required.
WHO and the Centers for Disease Control and Prevention continue to claim that when it comes to COVID-19, the general public has to worry about two types of transmission. One involves inhaling droplets from an infected person who is close by and the other involves touching a surface that is contaminated with the virus and then touching your eyes, nose, or mouth. Now this group of scientists from 32 countries says WHO needs to recognize that the virus lingers in the air in closed spaces and can also infect people that way. Although the scientists acknowledge that the coronavirus isn’t something like measles that can easily transmit through the air, the risk is real, particularly in poorly ventilated rooms and confined spaces like public transportation.
For now, WHO has said airborne transmission is really only a factor of concern after medical procedures such as intubations. Members of the organization’s infection prevention committee have said that while this could play some role, it was not truly significant and measures to guard against it would be unfeasible. “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,” Benedetta Allegranzi, WHO’s technical lead on infection control, tells the New York Times. “There is a strong debate on this.”
Some scientists, though, insist that WHO is ignoring the latest research in part due to bureaucratic issues that make it difficult for the organization to shift gears when faced with new evidence. They say there are plenty of examples, including infections in slaughterhouses and restaurants, that show airborne transmission is a real concern. One expert who signed the letter explained to the Times that part of the problem is that WHO relies on studies from hospitals that show there is little of the virus in the air. But in other buildings “the air-exchange rate is usually much lower, allowing virus to accumulate in the air.”
This is hardly the first time in this pandemic that the WHO has been accused of being too slow to adapt to new evidence. The most notorious example of this is how slow it was to back the suggestion that people should cover their nose and mouth while out in public and around other people. It has also been slow to recognize the importance of transmission from people who do not have symptoms.