Coronavirus, masks for everyone? Scientific studies in favor
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April 3, 2020
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April 7, 2020
Masks for everyone? Two solid scientific studies, published by MIT (MIT) and from Nature Medicine, suggest the effective utility of their widespread use to reduce the risks of spreading the coronavirus pandemic. Although the WHO continues to recommend its use only to people who are sick following the infection, caregivers and healthcare personnel.
In Italy meanwhile, on 3-4.4.20, the Regions of Lombardy, Veneto and Tuscany have imposed on their 19 million inhabitants the continuous coverage of the face when leaving the house, on the rare occasions admitted. Even if using a scarf, a bandana or a bandana keffiyeh. Or a scarf, waiting to receive the facemask.
Use of templates, the OMS / WHO position
On 30.3.20 the WHO (World Health Organization) reaffirmed that face protection devices (masks and respirators) should be used by three categories of subjects:
- health and social health personnel in contact with the virus,
- sick people who have contracted the virus,
- people who assist people in home isolation because they are infected.
Michael J. Ryan, executive director of the WHO Program for Health Emergencies, limited himself to highlighting the psychological and social benefits, with respect to a possible mass use of masks. However, underlining that confirmed scientific data could not demonstrate advantages in terms of slowing down the spread of Covid-19. (2)
Indeed, according to the WHO, improper use of the devices could be dangerous and even facilitate the transmission of the coronavirus. (3) More plausible is the note on the need to prefer the supply of stocks of devices available to those - especially in healthcare - who are exposed to the risk of contagion every second of every day. (4)
The only measures which so far have proved valid, according to WHO, are:
1) home isolation,
2) hand hygiene,
3) the rules of social distancing.
Useful clarification, home isolation is proving problematic since, following the lockdown located in many of the 207 countries now touched by Covid-19 (data as of 3.4.20), the home often becomes the place of transmission of the virus par excellence.
Spread of the virus in the air, the scientific study of MIT
David Heymann, an infectious disease specialist in the service of the WHO for over twenty years, highlighted the results of a study by MIT (MIT) that Covid-19 virus particles could spread up to 7-8 meters after an infected person exhales, coughs or sneezes. (5)
The MIT study exceeds the traditional approach of analyzing the spread of respiratory infectious diseases, which insists on the dichotomy between droplets (droplets with a diameter> 5-10 µm, which tend to fall to the ground within a short distance from who generated them and can contaminate the surfaces) and droplets nuclei (microscopic particles, <5μm, with greater persistence in the air) . (6)
Researchers instead they referred to previous studies by the University of Cambridge, where it was shown that exhalations, sneezing and coughing are constituted not only by mucus-salivary droplets but above all by a turbulent multi-phase cloud of gas. (7) A sort of aerosol that traps particles, mixing them with the air, delays their evaporation and facilitates their diffusion. By transporting them - depending on the speed with which they are emitted, the physiology of the patient, the external conditions (humidity, temperature, air flows) - up to 7-8 meters away.
A small study on SARS-CoV-2 in turn, he demonstrated the circulation of the virus (without ascertaining its active state) in the ventilation systems of the hospitals where three infected patients were hospitalized. The cases considered are certainly not representative and nevertheless confirm what MIT has verified. (8)
Recommendations on use masks could therefore be reconsidered, in the sense of promoting their use by entire populations. Lydia Bourouiba, the first author of the MIT study, however, highlights the need to ascertain at the same time the filtering power of current devices with respect to aerosol. Since 'ccurrently used surgical and N95 masks are not tested for these potential characteristics of respiratory emissions'. (6)
Effectiveness of surgical masks, the Hong Kong study
Nature Medicine has in turn published a study on the transmission of different types of seasonal human coronaviruses, influenza viruses and rhinoviruses, based on experimental tests conducted on volunteers in the Hong Kong Special Administrative Region, between 2013 and 2016.
'Surgical face masks significantly reduced detection of influenza virus RNA in respiratory droplets and coronavirus RNA in aerosols, with a trend towards reduced detection of coronavirus RNA in respiratory droplets. Our results indicate that surgical masks could prevent the transmission of human coronaviruses and influenza viruses from symptomatic individuals. ' (10)
WHO could therefore re-evaluate the opportunity to suggest to the whole world to protect the face. Reconsidering, in the light of the latest studies cited, what has already emerged in the study of the University of Birmingham, published in the New England Journal of Medicine on 17.3.20. (9) Where transmission of SARS-CoV-2 by air (via aerosol) has been demonstrated, with its possible stay in the air up to 3 hours and transmission capacity greater than the safe distance indicated by WHO (1 meter) .
Dario Dongo and Marina De Nobili
Note
(1) https://www.who.int/emergencies/diseases/novel-coronavirus-2019/media-resources/press-briefings
(2) The mass use by communities avoids for example the stigmatization of the positives at Covid-19. Shuo Feng, Chen Shen, Nan Xia, Wei Song et al. (2020). Rational use of face masks in the COVID-19 pandemic. The Lancet - Respiratory medicine, https://doi.org/10.1016/S2213-2600(20)30134-X
(3) The mass use of masks can induce an illusory sense of security and decrease the level of attention to be paid during outings, being victims of a false feeling of security. It must therefore be remembered that the mask or respirator does not make you immune
(4) Response by Michael J. Ryan (Executive Director of the WHO Health Emergencies Program) to a journalist who asked about the Austrian obligation to wear face masks in supermarkets
(5) Dr. Heymann, statement to the BBC, 2.4.20, https://www.bbc.com/news/science-environment-52126735
(6) Bourouiba L. (2020). Turbulent Gas Clouds and Respiratory Pathogen Emissions: Potential Implications for Reducing Transmission of COVID-19. JAMA, Published online March 26, 2020. doi: 10.1001 / jama.2020.4756 (https://jamanetwork.com/journals/jama/fullarticle/2763852 )
(7) - Scharfman BE, Techet AH, Bush JWM, Bourouiba L. Visualization of sneeze ejecta: steps of fluid fragmentation leading to respiratory droplets. Exp Fluids. 2016; 57:24. doi: https://doi.org/10.1007/s00348-015-2078-4
Bourouiba L., Dehandshoewoercker E., Bush J.WM. Violent respiratory events: on coughing and sneezing. J Fluid Mech. 2014; 745: 537-563. doi: https://doi.org/10.1017/jfm.2014.88
(8) Ong SWX, Tan .YK, Chia PY, et al. Air, surface environmental, and personal protective equipment contamination by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) from a symptomatic patient, JAMA. Published online March 4, 2020. doi: 10.1001 / jama.2020.3227
(9) Van Doremalen N., Bushmaker T, Morris DH, Holbrook MG, Gamble A, Brandi N, et al. Aerosol and Surface Stability of SARS-CoV-2 as Compared with SARS-CoV-1. The New England Journal of Medicine. 17.3.20. doi: 10.1056 / NEJMc2004973
(10) Nancy HL Leung, Daniel KW Chu et al. Respiratory virus shedding in exhaled breath and efficacy of face masks. Nat Med (2020). https://doi.org/10.1038/s41591-020-0843-2
(11) Ministry of Health, Italy, Covid, FAQ n. 4. What can I do to protect myself? http://www.salute.gov.it/portale/nuovocoronavirus/dettaglioFaqNuovoCoronavirus.jsp?lingua=italiano&id=228#6
(12) ISS Infection Prevention and Control Working Group. Iinterim indications for a rational use of the protections for Sars-Cov-2 infection in health and social-health activities (assistance to subjects affected by Covid-19) in the current Sars-Cov-2 emergency scenario. National Institute of Health (ISS), ISS Covid-19 Report 2/2020, 28.3.20
Dario Dongo, lawyer and journalist, PhD in international food law, founder of WIISE (FARE - GIFT - Food Times) and Égalité.
Graduated in law in Trento, she follows a master's degree in food law at Roma Tre. She is passionate about food and wine, she is between culture and tradition.
