NEW YORK CITY, July 7 (WNM/Johns Hopkins Center for Health Security) – The WHO, US CDC, and other experts have continually emphasized that respiratory droplets are the main driver SARS-CoV-2 transmission; however, 239 scientists from 32 countries are reportedly challenging (https://www.nytimes.com/2020/07/04/health/239-experts-with-one-big-claim-the-coronavirus-is-airborne.html) that notion in an open letter to the WHO. The authors argue that airborne transmission may be playing a larger role in the pandemic than previously believed, which would significantly impact future prevention strategies and the resources needed to fulfill them. While droplet transmission risk can be mitigated via physical distancing and barriers like face shields and face masks, airborne transmission would mean that virus particles could linger in the air for prolonged periods of time or travel (https://news.harvard.edu/gazette/story/2020/06/air-conditioning-may-be-factor-in-covid-19-spread-in-the-south/) longer distances, including via ventilation systems, instead of quickly settling on surfaces. If this is the case, mask usage could be necessary in many more environments, particularly indoors, even if the recommended physical distancing (e.g., 6-foot separation) is maintained. Additionally, individuals at elevated exposure risk, such as healthcare workers, could need N95 respirators instead of surgical or medical masks.
The existing WHO guidance emphasizes that aerosol transmission is possible (https://www.who.int/publications/i/item/WHO-2019-nCoV-IPC-2020.4), including during aerosol-generating medical procedures, but it is not a primary driver of community transmission. The authors of the forthcoming letter criticize (https://www.washingtonpost.com/world/europe/coronavirus-airborne-spread-world-health-organization/2020/07/05/9de19c38-bed8-11ea-b4f6-cb39cd8940fb_story.html) the WHO’s unwillingness to address emerging evidence supporting the role of aerosol/airborne transmission. Experts broadly acknowledge the difficult task the WHO faces in developing universal guidance for the world and navigating a complex political climate on a tight budget, but some believe that the WHO should reconsider the evidence. The letter will reportedly be published in the journal Clinical Infectious Diseases in the coming days.