1 Homemade cloth face 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 ? 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 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 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 or even a 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 from 1910-1911 67 physicians who were thought to be more disciplined in wearing masks of 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. To date 104 no randomized study has been conducted with an appropriate design to test if public masking works to 105 drive down transmission, and so we are left to assess observational studies in our attempts to know 106 whether public masking is beneficial. 107 We can learn from the 2003 SARS epidemic. Lo and colleagues examined the incidence rate of 108 influenza, respiratory synctitial virus (RSV), parainfluenza virus, and adenovirus from 1998 to 2003 in 109 Hong Kong.23 During the 2003 SARS epidemic in Hong Kong various public health measures were more 110 widespread in the community, including an estimated 76% of the population wearing a face mask. That 111 season the incidence of non-SARS respiratory viruses was greatly reduced compared to previous years. 112 Although difficult to disentangle public masking from handwashing, the results suggest that public 113 masking at least contributed to a huge reduction in respiratory illness. Case-control studies from the 114 outbreak confirm that face masks were indeed protective.24,25 Models based on these data suggest that 115 masking high proportions of the population could actually interrupt transmission of influenza virus.26

116 Comparing historical studies, filtration experiments, and observational studies to

117 the SARS-CoV-2 pathogen. 118 None of the historical studies, filtration experiments, or observational studies examined the SARS- 119 CoV-2 pathogen itself. We can, however, make inferences about the effectiveness of masks and different 120 materials on the size of the pathogens that were studied. Table 1 provides the sizes of the different 121 pathogens the various studies examine relative to the size of SARS-CoV-2 (0.1µm in diameter).27

4 122 Table 1: Size of various pathogens tested in the assessment of cloth masks.

Relative size compared Pathogen (disease) Pathogen size Study to SARS-COV2 (0.1µm) Adenovirus 0.09-0.1 Similar size Lo 200523 Bacillus atrophaeus 0.95-1.25µm ~10 times larger Davies et al. 201316 Bacteriophage MS2 0.023µm 5 times smaller Davies et al. 201316 Corynebacyerium diphtheriae 1µm 10 times larger Weaver 19189 (diptheria) Influenza 0.08-0.12 Similar size Lo 200523 Measles 0.1-0.3 Similar size Capps 191811 Mycobacterium tuberculosis 0.2-0.5µm 2-5 times larger (tuberculosis) Parainfluenza 0.15-0.25 Slightly larger Lo 200523 Respiratory syncytial virus 0.15-0.25 Slightly larger Lo 200523 Streptococcus pyogenes (scarlet Weaver 19189, < 2µm < 20 times larger fever) Capps 191811 Yersinia pestis (plague) 0.75µm 7.5 times larger Kool 20058 123

124 Conclusion – a call to action 125 The evidence from historical studies, filtration studies, and observational studies combined with the 126 simple logic of masking asympomatic transmitters of SARS-CoV-2 together suggests that mass public 127 masking may be an important public health intervention. And yet the WHO and CDC have advised 128 against the public wearing masks in community settings due to a lack of available evidence. They do not 129 “know” whether public masking is effective - there have not been community randomized trials of public 130 mask wearing to reduce infections. This argument is deeply flawed. It discounts the body of evidence that 131 exists simply because there are no randomized trials. Given the evidence should there even be randomized 132 trials including an arm withholding a cloth mask from a population? Would it be ethical to randomize 133 entire communities to not wear masks? And, can we wait for randomized trials before we take action? 134 Social distancing is in full force. The schools are closed. Non-essential businesses are shuttered. 135 People are under shelter-in-place orders. And yet all this action has been rightfully taken to stop COVID- 136 19 despite having no randomized trials of social distancing to inform our action. The available science 137 suggests that social distancing is effective, including numerous observational studies and modeling.28–34

5 138 But there is no “lack of available evidence” argument against social distancing as there is against masking 139 the public. 140 Ours is not the first time that the wearing of masks as a way to reduce transmission of infectious agents 141 has been questioned. Following the advent of antibiotics in the 1940s various medical doctors advocated 142 against mask wearing, wondering what the point of it was if they could simply treat the infections with 143 antibiotics.7 Fortunately medical doctors agitating against mask wearing were overruled. 144 The weight of the evidence suggests that we should add public masking to social distancing in this 145 fight against SARS-CoV-2. And so I reiterate the call for mass public masking.35 This call has a caveat 146 though – save the surgical masks and N95 respirators for frontline health workers! They face the greatest 147 dangers and should have the best equipment. Let us instead scale up production of homemade cloth masks 148 and do what we can to reduce transmission of SARS-CoV-2. With a variety of freely available templates 149 and guidelines online, and a glut of free time (put the puzzle away, get out the sewing machine), masking 150 the public with homemade cloth face masks could help turn the tide of this pandemic and more quickly 151 return society to being social.

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