In full awareness to COVID–19 and its transmission, I, the undersigned, call on the World Health Organization (WHO) to investigate the following:
I appeal to the medical community and to the relevant national and international bodies to recognize the potential for airborne spread of COVID-19. There is significant potential for inhalation exposure to viruses in microscopic respiratory droplets (microdroplets) at short to medium distances (up to several meters, or room-scale), and we are advocating for the use of preventive measures to mitigate this route of airborne transmission.
Studies by the signatory and other scientists have demonstrated beyond any reasonable doubt that viruses are released during exhalation, talking, and coughing in microdroplets small enough to remain aloft in the air and pose a risk of exposure at distances beyond 1 to 2 m from an infected individual.
Many studies conducted on the spread of other viruses, including respiratory syncytial virus (RSV), Middle East Respiratory Syndrome coronavirus (MERS-CoV), and influenza, show that viable airborne viruses can be exhaled or detected in the indoor environment of infected patients. This poses the risk that people sharing such environments can potentially inhale these viruses, resulting in infection and disease. There is every reason to expect that SARS-CoV-2 behaves similarly and that transmission via airborne microdroplets is an important pathway. Viral RNA associated with droplets smaller than 5 μm has been detected in air, and the virus has been shown to maintain infectivity in droplets of this size. Other viruses have been shown to survive equally well, if not better, in aerosols compared to droplets on a surface.
The evidence is admittedly incomplete for all the steps in COVID-19 microdroplet transmission, but it is similarly incomplete for the large droplet and fomite modes of transmission. The airborne transmission mechanism operates in parallel with the large droplet and fomite routes. Following the precautionary principle, we must address every potentially important pathway to slow the spread of COVID-19. The measures that should be taken to mitigate airborne transmission risk include:
• Provide sufficient and effective protective measures to control the risk o transmission of the virus.
• Supplement general ventilation with airborne infection controls such as local exhaust, high-efficiency air filtration, and germicidal ultraviolet lights.
• Prolonged antimicrobial protection using any topical formulation for extended hours up to 24 hours.
• Avoid overcrowding, particularly in public transport and public buildings.
I am concerned that the lack of recognition of the risk of airborne transmission of COVID-19 and the lack of clear recommendations on the control measures against the airborne virus will have significant consequences: people may think that they are fully protected by adhering to the current recommendations, but in fact, additional airborne interventions are needed for further reduction of infection risk.
This matter is of heightened significance now, when countries are re-opening following lockdowns - bringing people back to workplaces and students back to schools, colleges, and universities. I hope that my statement will raise awareness that airborne transmission of COVID-19 is a real risk and that control measures, as outlined above, must be added to the other precautions taken, to reduce the severity of the pandemic and save lives.
Together with the authors, 239 scientists support this Commentary, and their affiliations and contact details are listed in the Supplementary.
The following scientists contributed to formulating this commentary:
Linsey C. Marr, William Bahnfleth, Jose-Luis Jimenez, Yuguo Li, William W. Nazaroff, Catherine Noakes, Chandra Sekhar, Julian Wei-Tze Tang, Raymond Tellier, Philomena M. Bluyssen, Atze Boerstra, Giorgio Buonanno, Junji Cao, Stephanie J. Dancer, Francesco Franchimon, Charles Haworth, Jaap Hogeling, Christina Isaxon, Jarek Kurnitski, Marcel Loomans, Guy B. Marks, Livio Mazzarella, Arsen Krikor Melikov, Shelly Miller, Peter V. Nielsen, Jordan Peccia, Xavier Querol, Olli Seppänen, Shin-ichi Tanabe, Kwok Wai Tham, Pawel Wargocki, Aneta Wierzbicka, Maosheng Yao.
Dr. Vinay Kumar
Ph.D. Indian Institute of Technology (IIT) Delhi,
Head R&D Clensta International Pvt. Ltd.