27 Apr 2020

Scientific evidence on the possible use of medical masks by the general population during the COVID-19 pandemic

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From Elina Ioannou, RD, PhD Student, Cyprus International Institute of Environmental and Public Health, Cyprus University of Technology and Dr. Konstantinos C. Makris, Associate Professor of Environmental Health, Cyprus International Institute of Environmental and Public Health, Cyprus University of Technology.

 

A lot of discussion has sparked on whether asymptomatic individuals in the community setting should wear a medical  mask during the COVID-19 pandemic as an effective means of lowering the risk of being infected with the SARS-CoV-2 virus, which is primarily transmitted via respiratory or salivary droplets/aerosols. This viewpoint will focus on medical masks, because this is the most popular type of masks among the general public. Our analysis is aligned with the recommendations and considerations of international organizations and it will be composed of the following subsections: i) who should use them, ii) scientific evidence on the use of medical  mask in the community and iii) for how long such a  mask should be used.

 

It is important to state that the use of medical masks by health care professionals is warranted. This occupational group is well trained in the use of personal protective equipment; the use of masks is part of their usual daily professional routine and not only during this pandemic.

 

Who should use medical masks?

Based on the global literature,1-2 the use of medical masks in the community during the COVID-19 pandemic is not recommended for all. Medical masks could lower the risk of transmission when used as source control by reducing the number of viral copies that escape the mask, or pass through the mask.5 However, there is inadequate scientific evidence that the use of medical  masks could clearly lower the risk of viral infection in the general population. 1-2,4

Based on recommendations by the World Health Organization (WHO) 4 and the European Center for Disease Control and Prevention (ECDC), 5 a medical mask is prioritized for:

  1. patients with COVID-19 disease, or persons positively tested to the SARS-CoV-2 virus and
  2. care givers of COVID-19 patients.

The WHO and the ECDC state that the use of medical mask alone may not be effective in lowering the risk of SARS-CoV-2 infection, unless combined with additional measures which, -in some cases- can be even more effective. More specifically, WHO advises local public health organizations to consider a multi-ted approach regarding the possible use of medical mask in their community during this pandemic. Such an approach should take into account the population characteristics and lifestyle/cultural habits, the most common exposure events to the virus, the vulnerability of specific subpopulation groups (e.g. certain occupational groups that require frequent physical contact with others at work), the population density and spatial characteristics of crowded places. 4 

Scientific evidence on the use of medical masks in the community

The use of a medical mask belongs to the suite of non-pharmacological intervention (NPI) measures that aim to lower the risk of viral infection. Other examples of NPIs include hand hygiene, social distancing, and minimal physical distance. There are approximately 10 clinical trials on the effectiveness of medical mask use in reducing the risk of infection with either SARS-1 epidemic or seasonal influenza.1 Most of these clinical trials showed that the use of medical masks did not lower the viral infection risk, unless combined with hand hygiene, or applying of mask within 36 hours since the onset of symptoms.1  When analyzing the results of these studies, however, one should take into account the level of compliance, and the time period that the mask was correctly applied. It has been shown that the level of compliance to the use of medical mask during these studies was lower as time of continuous mask usage increased.1 It should be noted that current NPI recommendations for the COVID-19 pandemic are primarily based upon studies on the infection characteristics of flu and other respiratory infections. WHO strongly encourages countries that issue recommendations for the use of masks in healthy individuals in the community to conduct research on this critical topic.4

The most frequently tested NPI for its effectiveness in lowering the viral infection risk in the community was hand hygiene measures rather than the use of medical masks. A number of clinical trials implemented in the community setting, 6-7 have shown that the thorough hand washing hands was the most effective measure of self-protection against respiratory (flu, H1N1, etc.) and gastroenterological infections. A false protective perception may often prevail while someone wears a medical mask, which in turn could lead to avoiding the implementation of other protective measures, such as hand washing. International organizations clearly mention that the basic principles of self-protection from respiratory infections (such as hand hygiene) should not be neglected when people choose to use a medical mask.

 

Medical mask usage and disposal

Medical masks are disposable and should not be reused. After single use, medical masks should be carefully disposed, following the recommendations of the World Health Organization3 and the manufacturers’ guidelines. Additionally, those in the general population should prudently exercise the use of medical masks; if every single citizen were to daily use a medical mask, then we would soon risk facing shortage of masks for those that mostly need them, i.e., the health care professionals.

 

Recommendations on personal protection measures

When necessary, the use of medical masks in the community should be performed following the recommendations of the manufacturer and those of international organizations (WHO) in order to minimize possible contamination risk. 3 In any case though, the use of medical masks, when and if needed by the general population should not come at the expense of key personal protection measures as dictated by the international organizations (WHO, ECDC).4,5,8 These measures include:

  1. thorough and frequent hand washing with soap and water, or alternatively using an alcohol-based solution
  2. keeping physical safety distance of 1-2 meters
  • avoiding touching the face, nose, eyes and mouth.

 

These are the main self-protection measures recommended for the general population during a pandemic that relates to respiratory symptoms.

 

References

  1. MacIntyre, CR., & Chughtai, AA. (2015). Face masks for the prevention of infection in healthcare and community settings. BMJ, 350(apr09 1), h694–h694. doi:10.1136/bmj.h694
  2. Desai A.N.;  Mehrotra Ρ. (2020). Medical masks. JAMA. doi:10.1001/jama.2020.2331
  3. WΗΟ (2020). Coronavirus disease (COVID-19) advice for the public: When and how to use masks, http://www.who.int/emergencies/diseases/novel-coronavirus-2019/advice-for-public/when-and-how-to-use-masks (accessed on 12 April, 2020)
  4. WHO (2020). Advice on the use of masks in the context of COVID-19, Interim guidance, 6 April 2020.
  5. ECDC (2020). Using face masks in the community, technical report. Stockholm, Sweden, April 8, 2020.
  6. Rabie T, Curtis V. (2006). Handwashing and risk of respiratory infections: a quantitative systematic review. Trop Med Int Health; 11:258-67.
  7. Luby SP, Agboatwalla M, Feikin DR, Painter J, Billhimer W, Altaf A, et al. (2005). Effect of handwashing on child health: a randomised controlled trial. Lancet; 366:225-33.
  8. CDC (2020). How to protect yourself and others. https://www.cdc.gov/coronavirus/2019-ncov/prevent-getting-sick/prevention-H.pdf