Homemade Cloth Face Masks to Fight the COVID19 Pandemic: a Call

1 Homemade cloth face masks to fight the COVID19 pandemic: a call 2 for mass public masking with homemade cloth masks. 3 David A. Larsen PhD MPH1 4 Syracuse University Department of Public Health 5 Syracuse, New York, USA 6 Abstract 7 As we face the COVID-19 pandemic our country is largely ignoring a potential transmission control 8 tool – the community’s use of facial masks in public spaces. Ample evidence from historical studies 9 (early 1900’s), modern filtration experiments of different materials and pathogens, and observational 10 studies exists to suggest that mass masking of the community would decrease the transmissivity of SARS- 11 CoV-2 and accelerate the flattening of the curve in which we are engaged. The WHO and CDC claim a 12 lack of randomized trials as rationale for not promoting community use of face masks. But we have shut 13 down the schools, workplaces, and social events. Where are the randomized trials of social distancing? 14 We trust the science on social distancing. Let us trust the science on the community use of face masks. 15 Given the aggressive nature of the pathogen we face we should bring all potential interventions to the 16 fight against COVID-19, including the mass use of face masks of the community. With potentially 17 devastating shortages of N95 respirators and surgical masks for clinicians, community masks should be 18 homemade cloth that are effective at acting as source control interventions. Let us scale up the fabrication 19 of a billion homemade cloth face masks and wear them in public. 20 Introduction 21 As an uncouth American I used to smile at seeing people wearing face masks in public places. I 22 presumed that the people under the mask were germophobic. With the escalating SARS-CoV-2 pandemic 23 I have revised my thinking substantially. I now salute these individuals, with courage enough to brave the 24 stares and snickers. They are not just protecting themselves, they are protecting others. 25 Two major factors inform this change of thought. First, a large proportion of SARS-CoV-2 infections 26 are asymptomatic.1 I am encouraged when I see others in a mask because their actions provide me with 27 some protection against any asymptomatic infection they are potentially carrying. Second, wearing masks 28 at a population level may work to reduce transmission at the population level. In this essay I will address 29 the evidence that we do have regarding mask wearing, and why we need a billion homemade cloth mask 30 challenge. (I will not mention that the only countries that have been able to control this virus as of March 31 26, 2020 have a culture of mask wearing.) 1 32 Let me emphasize here though that the population should begin wearing cloth masks (even homemade 33 cloth masks). In the US as in other countries the growing COVID-19 pandemic has strained medical 34 supplies and shortages are faced in key areas including N95 respirators and surgical masks. (Preliminary 35 reports out of Wuhan suggest that N95 respirators were highly effective at preventing SARS-CoV-2 36 transmission to clinicians).2 Thus, to begin wearing an N95 respirator or even a surgical mask in public 37 would take these infection-preventing tools away from medical providers who need them most. 38 Cloth masks as infection prevention tools 39 The cloth face mask is widely used throughout the world by medical professionals, particularly in 40 lower income countries. When trying to determine if cloth face masks are effective at preventing 41 infections, however, recent studies have reported on a lack of evidence. A 2013 review suggested that 42 there were large evidence gaps in regards to cloth masks as a measure to decrease risk of respiratory 43 infections, primarily because there were no randomized trials of wearing cloth masks.3 Chughtai et al. 44 2013 discount the numerous historical studies it identifies because they were not randomized trials and 45 erroneously concludes that there is insufficient evidence to suggest that homemade cloth masks are better 46 than nothing. The authors fall into a common trap, that of thinking there is no evidence without a 47 randomized trial. Smith and Pell humorously elucidated this trap, as they concluded that it remains 48 inconclusive if parachutes reduce death as there have been no randomized trials.4 49 Following Chughtai et al.’s conclusions, a community-randomized controlled trial was conducted in 50 Viet Nam to examine the effectiveness of cloth masks to reduce transmission of influenza-like illness to 51 healthcare workers.5 This study compared an arm where health care workers wore cloth masks to an arm 52 where healthcare workers wore medical masks and found that influenza-like-illness was 50% more 53 common in the cloth mask arm. Importantly, this trial did not compare cloth masks to no masks - the 54 ethics review for the trial would not even allow an arm of no masks. Therefore, the control arm was 55 standard of care, which was a mix of cloth masks, medical masks, and even N95 respirators. If it is 56 unethical to randomize a healthcare worker to no mask, surely then a cloth mask is better than nothing? 57 (As my brother wisely joked, “I’d rather have boots in the snow. But if I don’t have boots, I’ll wear the 58 tennis shoes or even sandals before going barefoot.”) 59 Given that the ethics of modern medical science do not allow for withholding a cloth mask in a 60 controlled experiment, what evidence does exist that a cloth homemade mask might be beneficial at all? 61 For that we turn to historical studies of cloth masks in health workers (from the early 1900’s) as well as 62 modern experiments of the filtration capacity of different masks. 2 63 Historical evidence of cloth masks for reducing infection 64 A German physician was the first to publish a study supporting the use of a surgical mask in 1897 and 65 the practice quickly increased among physicians (see Belkin 1997 and Rockwood 1960 for a thorough 66 review of the history of masks).6,7 During the first Manchurian plague epidemic from 1910-1911 67 physicians who were thought to be more disciplined in wearing masks of cotton gauze had far less 68 mortality than sanitary attendants and ambulance staff who were thought to be less disciplined in mask 69 wearing.8 In 1918 George Weaver reported that nurses wearing masks made of a three to four layers of 70 gauze led to a 65% reduction in diphtheria attack rates (from 23.3% of nurses contracting diphtheria 71 before using face masks to 8.2% of nurses contracting diphtheria after using face masks), and a complete 72 elimination of scarlet fever attack rates (from 8% of nurses contracting scarlet fever before using face 73 masks to 0% of nurses contracting scarlet fever after using face masks).9 These same masks were used by 74 Capps in 1918 to mask patients10 and reduce scarlet fever cross-infection by 95% and eliminate cross- 75 infection from measles in a military hospital.11 76 Numerous experiments with facial masks were conducted in the middle of the 20th century.12,13 These 77 experiments typically examined droplet spread comparing no mask to any mask as well as different types 78 of materials of masks. For example, Greene and Vesley found that gauze and flannel masks reduced 79 droplets by huge magnitudes, > 99% reductions for particles 4µm or larger and by 97% for particles < 80 4µm.14 And Quesnel found that four-ply cotton muslin reduced transmission of particles larger than 81 3.3µm by 96.7% and for particles £ 3.3µm by 89%.15 82 Modern experiments of filtration capacity of cloth masks 83 Fully cognizant that a mass influenza pandemic would overwhelm the supply and disrupt the 84 distribution of N95 respirators and medical face masks, numerous scientists have conducted experiments 85 with different types of materials to determine how well those materials filter various sized pathogens. The 86 most robust data come from a 2013 study examining different materials’ ability to filter either Bacillus 87 atrophaeus (larger than SARS-CoV-2) or the Bacteriophage MS2 (smaller than SARS-CoV-2).16 They 88 found homemade masks made with cotton blend materials were 78% as effective as medical masks at 89 filtering B. atrophaeus and 56% as effective as medical masks at filtering Bacteriophage MS2. And 90 although Rengasamy et al. found that cloth masks were quickly penetrated by molecules in the size range 91 of SARS-CoV-2, the range in penetration was similar to the penetration of surgical masks.17 Even 92 facemasks improvised from t-shirts provide relatively good protection.18 3 93 Evidence of public masking to reduce infectious disease transmission 94 Public masking theoretically works to drive down transmission at the population level. When a large 95 portion of the population is wearing masks, both asymptomatic spreaders of the pathogen as well as the 96 healthy will be masked. The key to public masking as transmission control is in source reduction. Putting 97 masks on the sick reduces their ability to spread the virus. Unfortunately, randomized trials to examine 98 the effectiveness of public masking have not designed their studies with these dynamics in mind. Instead 99 the trials have looked at public masking to prevent getting sick, rather than as a source reduction. The 100 majority of trials have examined masking within households, when it is known that someone else in the 101 household is sick,19–21 and others have not masked entire communities.22 These studies are not designed to 102 test whether public masking reduces disease transmission – ideally we would have entire communities 103 randomized to masking or not and observe the incidence of illnesses within those communities.

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