What type of mask should healthcare workers use to protect from novel coronavirus diseases (COVID-19) pandemic?

Abrar Ahmad Chughtai, School of Public Health and Community Medicine, UNSW

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV2) emerged in Wuhan City in China in December 2019 and as of 25 June 2020, around 9 million cases and 0.5 million deaths have been reported globally (1) . Like severe acute respiratory syndrome coronavirus1 (SARS-CoV1), Ebola and other previous epidemics (2, 3) , many frontline health workers have already been infected with coronavirus diseases (COVID-19) pandemic (4) . In addition to other infection control strategies, health workers are advised to use masks/respirators to protect from infection. During the initial phase of COVID-19 pandemic, health organisations and countries had different policies around use of masks and respirators to protect from COVID-19 (5) . Some of them recommended using masks to protect health workers from COVID-19 during low risk situations (e.g. routine care of COVID-19 cases) and respirators during high risk situations (e.g. aerosol generating procedures), while others recommended respirators in both high and low risk situations (5) . However now most health organisations, including World Health Organization (WHO), the US Centers for Disease Control and Prevention (CDC) and the European Center for Disease Control (ECDC) have the uniform policy for healthcare workers, i.e. masks use during low risk situations and respirators use during high risk situations (6, 7) . The US CDC and the ECDC previously recommended respirator use in both low and high risk situations but recently changed their guideline (5, 8, 9) . However, the change in the guideline was not based on new evidence, rather it was due to shortage of respirators. Many countries still have varying policies, e.g. Australian (10) and Canadian guidelines (11) recommend the use of masks during low risk situations and respirators during high risk situations, while UK (12) and Chinese guidelines (13) recommend respirators in both situations.
Policies and guidelines of health organisations and countries on the use of masks or respirators are also inconsistent for other infections such as seasonal influenza, pandemic influenza , SARS-CoV1, Middle East respiratory syndrome coronavirus (MERS-CoV) and Ebola virus disease (14, 15) . The main difference between masks and respirators is the intended use. Masks were originally designed to prevent spread of infections from wearers to other people around (referred as “source control”). Masks are also used to protect wearer from splashes or sprays of blood or body fluids and droplet infections. In contrast to this, respirators are designed for respiratory protection and many studies show that properly fitted respirators are more protective compared to masks (16, 17) .
Like other coronaviruses (e.g. SARS-CoV1 and MERS-CoV), SARS-CoV2 is primarily transmitted thought the droplet and contact modes, however exact mode of transmission is not clear at this stage. Studies show that SARS-CoV2 may survive in air for up to 3 hours and there is also some evidence of airborne transmission of SARS-CoV2 (18-20) . During SARS-CoV1 epidemic in 2002-03, initially masks were recommended but later on changed to respirators due to risk of airborne
transmission. Transmission dynamics of a COVID-19 is still unclear and drugs and vaccines are also not available, therefore all healthcare workers should use N95, P2 or equivalent respirators (15, 16, 21) . Some studies during the COVID-19 pandemic also reported low rates of infection among healthcare workers who used respirators (22). Healthcare workers are at frontline during epidemics and pandemics and they need to be protected to maintain functional healthcare system. Therefore, infection control policies should be changed, respirators should be recommended for all frontline healthcare workers who are managing COVID-19 cases. However, if respirators are not available, then health workers may be advised to use a medical mask.

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2. World Health Organization (WHO). Cumulative Number of Reported Probable Cases of SARS [Available from: http://www.who.int/csr/sars/country/2003_07_11/en/.
3. World Health Organization (WHO). Health worker Ebola infections in Guinea, Liberia and Sierra Leone – A preliminary report. 2015.
4. Center for Infectious Diseases Research and Policy (CIDRAP). COVID-19 sickens over 1,700 health workers in China, killing 6 [Available from: http://www.cidrap.umn.edu/news-perspective/2020/02/covid-19-sickens-over-1700-health-workers-china-killing-6.
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7. European Centre for Disease Prevention and Control (ECDC). Infection prevention and control and preparedness for COVID-19 in healthcare settings Third update – 13 May 2020. http://www.ecdc.europa.eu/sites/default/files/documents/Infection-prevention-control-for-the-care-of-patients-with-2019-nCoV-healthcare-settings_third-update.pdf. 2020.
8. Center for Disease Control and Prevention (CDC). Interim Healthcare Infection Prevention and Control Recommendations for Patients Under Investigation for 2019 Novel Coronavirus. January 2020 2020 [Available from: http://www.cdc.gov/coronavirus/2019-nCoV/infection-control.html.
9. European Centre for Disease Prevention and Control (ECDC). Infection prevention and control for the care of patients with 2019-nCoV in healthcare settings 2020 [Available from: http://www.ecdc.europa.eu/sites/default/files/documents/nove-coronavirus-infection-prevention-control-patients-healthcare-settings.pdf.
10. Communicable Diseases Network Australia (CDNA). CDNA National Guidelines for Public Health Units [Available from:
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12. Public Health England. Guidance. COVID-19: infection prevention and control guidance
[Available from: http://www.gov.uk/government/publications/wuhan-novel-coronavirus-infection-prevention-and-control/wuhan-novel-coronavirus-wn-cov-infection-prevention-and-control-guidance.
13. Chinese Center for Disease Control and Prevention. New Coronavirus Pneumonia Prevention and Control Plan (Fourth Edition) 2020 [Available from:
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18. van Doremalen N, Bushmaker T, Morris DH, Holbrook MG, Gamble A, Williamson BN, et al. Aerosol and surface stability of SARS-CoV-2 as compared with SARS-CoV-1. New England Journal of Medicine. 2020.
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20. Liu Y, Ning Z, Chen Y, Guo M, Liu Y, Gali NK, et al. Aerodynamic characteristics and RNA concentration of SARS-CoV-2 aerosol in Wuhan hospitals during COVID-19 outbreak. bioRxiv. 2020.
21. MacIntyre CR, Chughtai AA, Seale H, Richards GA, Davidson PM. Uncertainty, risk analysis and change for Ebola personal protective equipment guidelines. Int J Nurs Stud. 2014;52(5):899-903.
22. Wang X, Pan Z, Cheng Z. Association between 2019-nCoV transmission and N95 respirator use. medRxiv. 2020 Jan 1.