Face mask use during the COVID-19 pandemic
(Opinion Piece by Scott McKechnie)
Face masks are widely used in Asia by both the public and healthcare providers. While much less common in Europe and North America, many countries are now reconsidering the role of masking. It is increasingly recommended and major health bodies like the World Health Organization (WHO), Centers for Disease Control and Prevention (CDC) and European Centre for Disease Prevention and Control (ECDC) have all revisited the question [1-4]. As it stands, there is no global consensus and strong empirical studies are lacking; however, there is a growing body of work and an emerging argument is that the absence of evidence is not evidence for absence [5-8]. This reduces to an ethical question and applying the precautionary principle points to mask usage on the grounds that we have little to lose but potentially something to gain. Universal cloth mask usage can be recommended for the public and, as a last resort, for healthcare providers when medical grade options are not available.
The case for universal face mask use (UFMU)
There are a number of potential advantages to universal masking and all rooted in the mechanistic reasoning that face masks limit droplet spread. It is often assumed that face masks are intended to protect the wearer but perhaps more importantly protect others by retaining droplets and controlling the harm at source. This is of particular importance for COVID-19 where viral load is high at early disease stage and there is documented asymptomatic transmission . The importance of reducing droplet spread and its role in transmission has been addressed by a number of authors. For instance, Javid et al. state the following : “Maximal viral shedding of SARS-CoV-2 (the cause of covid-19) occurs early in the course of the illness. Patients may therefore be contagious before they develop symptoms or even know that they are infected. Transmission of SARS-CoV-2 by asymptomatic individuals has been clearly documented, and mathematical models suggest that 40-80% of transmission events occur from people who are presymptomatic or asymptomatic. Sneezing and coughing may not be necessary; we know that patients with influenza shed substantial titres of infectious virions during normal breathing. Together, these data support the idea that seemingly well individuals shedding high titres of SARS-CoV-2 may represent a substantial risk for onward transmission.
Kaltenboeck et al. provide further detail :“The largest respiratory droplets, which are expelled by coughing, sneezing, or speaking, come from the pharynx and upper respiratory tract. This is also where the virus replicates the most. Volume is a cubic function, so these large droplets can hold exponentially more copies of the virus than small ones. The large ones quickly succumb to gravity due to their size, while the smaller aerosols, generated in the lower respiratory tracts of infected patients, can remain suspended in the air for several hours… even makeshift masks create a physical barrier that limits where these droplets can land. While wearing them doesn’t stop all exposure, it is curtailed, and studies of crude masks made from basic consumer materials suggest that they can make a difference… Perhaps more importantly, masks drastically reduce the number of droplets that make it beyond the wearer’s mask and into their surroundings. This insight may be critical for coronavirus. Preliminary analysis of nasals swabs from asymptomatic and symptomatic individuals indicate that they appear to have similar viral loads. Using a mask allows even those who do not suspect that they are infected to reduce the probability of transmission. Added to social distancing, this barrier could reduce the number of viral copies making contact with others and coming to rest on surfaces, waiting for the unwitting brush of a hand that later meets the face.“
And a modeling study by Eikenberry et al. in April 2020 concluded the following :“broad adoption of even relatively ineffective face masks may meaningfully reduce community transmission of COVID-19 and decrease peak hospitalizations and deaths.
Mask use is seen in many countries with better outcomes and curve flattening, even in the absence of a lockdown [5, 9, 11]. Masking may also play an increasingly important role as social restrictions are eased. A number of mask options are available and although surgical masks and respirators remain the preferred option in healthcare settings, cloth masks could be universally used with little cost. This is the approach adopted by the CDC and appears to be motivated by supply chain concerns for healthcare workers. Proper mask usage is of course critical but, as with handwashing, safe donning, use and doffing could be learned through public education. And as Javid et al. point out, “Importantly, if a mask is contaminated at removal, it has (by definition) already protected the wearer from contagious droplets.” On a final note, some critics say that masks could provide a false sense of security. This and other main arguments, have been robustly addressed by a number of authors [1-3,12].As MacIntyre et al. state:“Arguments that UFMU may give people a false sense of security and increase their infection risk are not supported by the evidence, which in fact shows the opposite. (4) Arguments against the use of other population health measures such as HPV vaccine (such as vaccination will increase risk of sexually transmitted infections by encouraging promiscuity) have similarly not been borne out by evidence. (16) There is more evidence supporting face mask use in the community than hand hygiene including in RCTs which compare both interventions directly, (4) so it is inconsistent to advocate hand hygiene as a sound principle but not masks.”Cloth masks
Cloth masks are commonly viewed as the third choice after respirators and surgical masks; although not ideal, they offer a sustainable option that doesn’t compete with supplies for healthcare workers [5-12]. It is worth noting the reports of repeated use of medical grade face masks (designed for single use) owing to critical shortages . Cloth masks can be manufactured at scale or made at home and are reusable with washing. Policy guidance on cloth masks is sparse but the CDC recently advised universal public use and as a last resort option for healthcare providers, points echoed by the Joint Commission, ECDC and the Royal Society [2-4,11,13]. Along with the US, other countries such as Germany are now embracing cloth mask use. The report from the Royal Society DELVE Initiative provides a summary of the different international responses as of May 4, 2020 .
The increased risk of older people and those with underlying conditions has focused attention on personal protective equipment shortages in healthcare centres. A survey of demand in Irish healthcare centres carried out by volunteers in the Team OSV community from 22 - 29 April, 2020 showed that face masks were the main concern, and some institutions were looking for thousands of medical grade masks a week. This adds to supply chain pressure. In this context,it is believed that cloth masks should be considered in situations of shortage, given that cloth masks are thought to be better than no mask at all. Conclusion
Universal cloth mask usage can be recommended for the public and, as a last resort, for healthcare providers when medical grade options are not available. I close with a succinct summary by Greenhalgh and colleagues: “in the face of a pandemic the search for perfect evidence may be the enemy of good policy. As with parachutes for jumping out of aeroplanes, it is time to act without waiting for randomised controlled trial evidence… they could have a substantial impact on transmission with a relatively small impact on social and economic life.”Notes on cloth mask use
“Community Universal Face Mask Use during the COVID 19 pandemic – from households to
travelers and public spaces”
“The filtration of different fabrics varies widely. For example, scarves and silk filter poorly, and cotton blend T-shirt material performs better than pure cotton. (15) Hydrophobic fabrics are best, and designs which have 2-3 layers and provide good fit around the face to prevent air leakage may be desirable. Daily washing of cloth masks used by community members is recommended to prevent self-contamination. It may even be wise to have 2 masks a day and change them during the day.” Author responses to “A cluster randomised trial of cloth masks compared with medical masks in healthcare workers”
“ If health workers choose to work using cloth masks, we suggest that they have at least two and cycle them, so that each one can be washed and dried after daily use. Sanitizer spray or UV disinfection boxes can be used to clean them during breaks in a single day. These are pragmatic, rather than evidence-based suggestions, given the situation.” References
 World Health Organization. 2020 Advice on the use of masks in the context of COVID-19. See https://www.who.int/publications-detail/advice-on-the-use-of-masks-in-the-community-during-home-care-and-in-healthcare-settings-in-the-context-of-the-novel-coronavirus-(2019-ncov)-outbreak
 Centers for Disease Control and Prevention. 2020 Recommendation Regarding the Use of Cloth Face Coverings, Especially in Areas of Significant Community-Based Transmission. See https://www.cdc.gov/coronavirus/2019-ncov/prevent-getting-sick/cloth-face-cover.html
 Centers for Disease Control and Prevention. 2020 Strategies for Optimizing the Supply of Facemasks. See https://www.cdc.gov/coronavirus/2019-ncov/hcp/ppe-strategy/face-masks.html
 European Centre for Disease Prevention and Control. 2020 Cloth masks and mask sterilisation as options in case of shortage of surgical masks and respirators. See “https://www.ecdc.europa.eu/sites/default/files/documents/Cloth-face-masks-in-case-shortage-surgical-masks-respirators2020-03-26.pdf
 Cheng KK et al. 2020 Wearing face masks in the community during the COVID-19
pandemic: altruism and solidarity. The Lancet (doi: 10.1016/S0140-6736(20)30918-1)
 Javid B, Weekes MP, Matheson NJ. 2020 Covid-19: should the public wear face masks? BMJ (doi: 10.1136/bmj.m1442).
 Greenhalgh T et al. 2020. Face masks for the public during the covid-19 crisis. BMJ (doi: 10.1136/bmj.m1435).
 Leung C C. 2020 Mass masking in theCOVID-19 epidemic: people need guidance. The Lancet (doi: 10.1016/S0140-6736(20)30520-1).
 Kaltenboeck A et al. 2020 The Case for Masks – Health Care Workers Can Benefit, Too. Mayo Clinic Proceedings (doi: 10.1016/j.mayocp.2020.04.014).
 Eikenberry et al. 2020 To mask or not to mask: Modeling the potential for face mask use by the general public to curtail the COVID-19 pandemic. Infectious Disease Modelling (doi: 10.1016/j.idm.2020.04.001).
 Royal Society DELVE Initiative. 2020 Face Masks for the General Public. See https://rs-delve.github.io/reports/2020/05/04/face-masks-for-the-general-public.html#fn:15
 MacIntyre C et al. 2020 Community Universal Face Mask Use during the COVID 19 pandemic—from households to travelers and public spaces. Journal of Travel Medicine (doi: 10.1093/jtm/taaa056)
 The Joint Commission. 2020 Joint Commission Statement on Use of Face Masks Brought From Home. See https://www.jointcommission.org/-/media/tjc/documents/resources/patient-safety-topics/infection-prevention-and-hai/covid19/public_statement_on_masks_from_home.pdf