Abstract

There is increasing evidence that the use of masks is an indispensable protective measure against COVID-19, given the high transmissibility of the new coronavirus through the respiratory system, including by asymptomatic individuals. The use of cloth masks in public places has been established as a protective measure to be adopted alongside social distancing and hand hygiene. This narrative review aims to systematize the scientific evidence that informs the widespread use of cloth masks as a preventive measure against COVID-19 and to describe the evolution of positions contrary to or in favor of its use outside the home, in view of the advance of the new coronavirus pandemic globally. The scientific articles, technical notes, governmental decrees and other documents analyzed indicate that widespread use of masks has the potential to reduce the spread of the new coronavirus. We recommend that the Brazilian government adopt strategies to increase the supply of reusable cloth masks to the public, especially to vulnerable populations and to support studies on the impact of this measure to control the pandemic in the country. Finally, it is imperative to ensure that use of masks does not exacerbate stigmatization of racial groups that already face prejudice.

Key words:
Cloth masks; Homemade masks; COVID-19; SARS-CoV-2; Novel coronavirus

Introduction

Since the emergence of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), there has been much debate on how best to control the pandemic in both the media and the scientific literature. The principal mechanism of human-to-human transmission of the novel coronavirus is known to be through inhalation of droplets generated from the nose or mouth of infected individuals by breathing, speaking, coughing or sneezing, irrespective of whether or not these individuals are ill or asymptomatic. In addition, the virus is able to remain viable and infectious in aerosols for up to three hours and on hard surfaces for up to 72 hours¹1 Centers for Disease Control and Prevention (CDC). Coronavirus Disease 2019 (COVID-19) - Prevention & Treatment [Internet]. Washington: CDC; 2020 [acessado 2020 Maio 4]. Disponível em: https://www.cdc.gov/coronavirus/2019-ncov/prevent-getting-sick/prevention.html

2 Ong SWX, Tan YK, Chia PY, Lee TH, Ng OT, Wong MSY, Marimuthu K. Air, Surface Environmental, and Personal Protective Equipment Contamination by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) From a Symptomatic Patient. JAMA 2020; 323(16):1610-1612.^-33 van Doremalen N, Bushmaker T, Morris DH, Holbrook MG, Gamble A, Williamson BN, Tamin A, Harcourt JL, Thornburg NJ, Gerber SI, Lloyd-Smith JO, Wit E, Munster VJ. Aerosol and Surface Stability of SARS-CoV-2 as Compared with SARS-CoV-1. N Engl J Med 2020; 382(16):1564-1567..

Because of the prolonged viability of the virus on some materials in the environment, and therefore the additional possibility of SARS-CoV-2 being transmitted through contact with contaminated surfaces²2 Ong SWX, Tan YK, Chia PY, Lee TH, Ng OT, Wong MSY, Marimuthu K. Air, Surface Environmental, and Personal Protective Equipment Contamination by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) From a Symptomatic Patient. JAMA 2020; 323(16):1610-1612.^,44 Kampf G, Todt D, Pfaender S, Steinmann E. Persistence of coronaviruses on inanimate surfaces and their inactivation with biocidal agents. J Hosp Infect 2020; 104(3):246-251., the initial recommendations to avoid dissemination of the disease involved extensive social distancing and regular, effective handwashing⁵5 Ghinai I, McPherson TD, Hunter JC, Kirking HL, Christiansen D, Joshi K, Rubin R, Morales-Estrada S, Black SR, Pacilli M, Fricchione MJ, Chugh RK, Walblay KA, Ahmed NS, Stoecker WC, Hasan NF, Burdsall DP, Reese HE, Wallace M, Wang C, Moeller D, Korpics J, Novosad SA, Benowitz I, Jacobs MW, Dasari VS, Patel MT, Kauerauf J, Charles EM, Ezike NO, Chu V, Midgley CM, Rolfes MA, Gerber SI, Lu X, Lindstrom S, Verani JR, Layden JE, Illinois COVID-19 Investigation Team. First known person-to-person transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in the USA. Lancet 2020; 395(10230):1137-1144.

6 World Health Organization (WHO). Shortage of personal protective equipment endangering health workers worldwide. Geneva: WHO; 2020.

7 Agência Nacional de Vigilância Sanitária (ANVISA). Orientações Gerais - Máscaras faciais de uso não profissional. Brasília: ANVISA; 2020.^-88 Brasil. Ministério da Saúde (MS). Nota Técnica: Uso de máscaras caseiras. Brasília: MS; 2020.. In the case of symptomatic patients or those who tested positive for SARS-CoV-2, the recommendation was self-isolation at home with quarantining of their respective contacts⁹9 World Health Organization (WHO). Responding to community spread of COVID-19: interim guidance [Internet]. Genebra: WHO; 2020 [acessado 2020 Maio 6]. Disponível em: https://apps.who.int/iris/handle/10665/331421.

As the pandemic advanced, the widespread use of facemasks in public spaces (commercial establishments, parks, the workplace, public transport, etc.) began to be discussed as a further means of protection, based on the accumulated experience of other countries in previous epidemics¹⁰10 Liang M, Gao L, Cheng C, Zhou Q, Uy JP, Heiner K, Sun C. Efficacy of face mask in preventing respiratory virus transmission: A systematic review and meta-analysis. Travel Med Infect Dis 2020; 36:101751.. The debate in favor of this proposal gained ground due to the role of asymptomatic, oligosymptomatic and presymptomatic individuals in disseminating the disease¹¹11 Tong Z-D, Tang A, Li K-F, Li P, Wang H-L, Yi J-P, Zhang Y-L, Yan J-B. Potential Presymptomatic Transmission of SARS-CoV-2, Zhejiang Province, China, 2020. Emerg Infect Dis 2020; 26(5):1052-1054.

12 Bai Y, Yao L, Wei T, Tian F, Jin D-Y, Chen L, Wang M. Presumed Asymptomatic Carrier Transmission of COVID-19. JAMA 2020; 323(14):1406-1407.^-1313 Kimball A, Hatfield KM, Arons M, James A, Taylor J, Spicer K, Bardossy AC, Oakley LP, Tanwar S, Chisty Z, Bell JM, Methner M, Harney J, Jacobs JR, Carlson CM, McLaughlin HP, Stone N, Clark S, Brostrom-Smith C, Page LC, Kay M, Lewis J, Russell D, Hiatt B, Gant J, Duchin JS, Clark TA, Honein MA, Reddy SC, Jernigan JA, Public Health - Seattle & King County, CDC COVID-19 Investigation Team. Asymptomatic and presymptomatic SARS-CoV-2 infections in residents of a long-term care skilled nursing facility-King County, Washington, March 2020. MMWR Morb Mortal Wkly Rep 2020; 69(13):377-381., in view of the evidence that the incubation period associated with COVID-19 is long¹⁴14 Wang Y, Wang Y, Chen Y, Qin Q. Unique epidemiological and clinical features of the emerging 2019 novel coronavirus pneumonia (COVID-19) implicate special control measures. J Med Virol 2020; 92(6):568-576.

15 Huang R, Xia J, Chen Y, Shan C, Wu C. A family cluster of SARS-CoV-2 infection involving 11 patients in Nanjing, China. Lancet Infect Dis 2020; 20(5):534-535.^-1616 Kraemer MUG, Yang C-H, Gutierrez B, Wu C-H, Klein B, Pigott DM, Open COVID-19 Data Working Group, du Plessis L, Faria NR, Li R, Hanage WP, Brownstein JS, Layan M, Vespignani A, Tian H, Dye C, Pybus OG, Scarpino SV. The effect of human mobility and control measures on the COVID-19 epidemic in China. Science 2020; 368(6490):493-497. and the understanding that the viral load is high in the initial stage of the disease¹²12 Bai Y, Yao L, Wei T, Tian F, Jin D-Y, Chen L, Wang M. Presumed Asymptomatic Carrier Transmission of COVID-19. JAMA 2020; 323(14):1406-1407.^,1717 Zou L, Ruan F, Huang M, Liang L, Huang H, Hong Z, Yu J, Kang M, Song Y, Xia J, Guo Q, Song T, He J, Yen H-L, Peiris M, Wu J. SARS-CoV-2 Viral Load in Upper Respiratory Specimens of Infected Patients. N Engl J Med 2020; 382(12):1177-1179.

18 Ma QX, Shan H, Zhang HL, Li GM. Potential utilities of mask-wearing and instant hand hygiene for fighting SARS-CoV-2. J Med Virol 2020; 92(9):1567-1571.^-1919 Ling Z, Xu X, Gan Q, Zhang L, Luo L, Tang X, Liu J. Asymptomatic SARS-CoV-2 infected patients with persistent negative CT findings. Eur J Radiol 2020; 126:108956..

The adoption of a universal policy on the use of disposable facemasks during the pandemic would lead to a demand that would be difficult to meet, resulting in shortages of protective equipment for healthcare professionals and other habitual users²⁰20 Wang M-W, Zhou M-Y, Ji G-H, Ye L, Cheng Y-R, Feng Z-H, Chen J. Mask crisis during the COVID-19 outbreak. Eur Rev Med Pharmacol Sci 2020; 24(6):3397-3399.^,2121 Feng S, Shen C, Xia N, Song W, Fan M, Cowling BJ. Rational use of face masks in the COVID-19 pandemic. Lancet Respir Med 2020; 8(5):434-436.. At the beginning of April, the World Health Organization (WHO) issued a recommendation that the use of disposable masks should be limited to healthcare professionals, immunosuppressed individuals, and suspected or confirmed cases of the novel coronavirus. The WHO also warned that there was a lack of evidence supporting the widespread use of masks made from other materials⁹9 World Health Organization (WHO). Responding to community spread of COVID-19: interim guidance [Internet]. Genebra: WHO; 2020 [acessado 2020 Maio 6]. Disponível em: https://apps.who.int/iris/handle/10665/331421. It was only on June 5, 2020 that the WHO issued guidelines on the use and fabrication of cloth masks to protect against COVID-19 and began to recommend their widespread use in places where transmission of the virus was high and in situations in which social distancing is impossible such as on public transport²²22 World Health Organization (WHO). Advice on the use of masks in the community, during home care and in healthcare settings in the context of the novel coronavirus (COVID-19) outbreak [Internet]. 2020 [acessado 2020 Maio 6]. Disponível em: https://www.who.int/publications/i/item/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.
https://www.who.int/publications/i/item/... .

The objective of the present paper was to perform a review of the literature about the efficacy of the use of cloth masks in public places for the prevention of COVID-19 and to describe the changes in opinion regarding their use outside the home as the novel coronavirus pandemic spread worldwide.

Methods

This narrative review initially involved a search for papers on the use of masks in the context of the new coronavirus published in the Medline database (PubMed), which includes peer-reviewed scientific publications²³23 Chen Q, Allot A, Lu Z. Keep up with the latest coronavirus research. Nature 2020; 579(7798):193., and the database Scielo, as well as preprints available in the MedRxiv databases, which are together the largest and most important repository of biomedical scientific literature.

To select relevant papers, we searched for the keywords “mask and covid” or “mask and coronavirus” or “mask and covid-19” or “mask and covid19” in the titles and abstracts of papers published up to June 12, 2020. Original articles, editorials, letters to the editor, comments and literature reviews in Portuguese, English or Spanish were included as long as the entire paper was available. Articles with data referring only to the use of surgical masks (TNT and similar), respiratory masks (N95, FFP2) and disposable masks; those dealing with masks designed to cover parts of the face other than the respiratory tract (e.g., eye masks and face shields) and those dealing with the use of masks exclusively by healthcare professionals were excluded from the review.

In addition to the scientific papers selected for inclusion, official state and federal documents implemented in Brazil, including decrees, statutes and state legislation available on LegisWeb²⁴24 LegisWeb. LegisWeb [Internet]. [acessado 2020 Set 29]. Disponível em: https://www.legisweb.com.br/
https://www.legisweb.com.br... , an online platform; technical notes from the Brazilian Ministry of Health and from the Brazilian National Health Surveillance Agency (ANVISA); and regulations adopted in other countries regarding the use of cloth masks in public spaces during the COVID-19 pandemic were also included. For adoption of cloth masks by other countries, information was obtained through the website of Masks4All²⁵25 Masks4All. What Countries Require or Recommend Masks In Public? [Internet]. [acessado 2020 Set 29]. Disponível em: https://masks4all.co/what-countries-require-masks-in-public
https://masks4all.co/what-countries-requ... , a non-governmental organization that gathers information on mask usage across the globe. All sources were consulted before June 12^th.

A quantitative synthesis of the most important findings from the selected articles was conducted, based on the following extracted data: authors, journal, title, publication date, type of publication, and authors’ recommendation regarding whether or not to use cloth masks as a means of preventing and controlling COVID-19 (Chart 1). The authors’ viewpoints were classified as: i) favorable; ii) no opinion or iii) opposed. The temporal evolution of these viewpoints was analyzed.

Additionally, we extracted information about the adoption and efficacy of cloth masks from the literature selected. A qualitative synthesis of these studies’ main findings, the arguments that support authors’ positions against or in favor of mask usage, as well as differences among countries was also conducted. In this way, all information obtained was synthesized and discussed based on existing published scientific evidence to date.

Results

Below, we present the results obtained through this narrative review, which is not intended to provide an extensive and detailed description of the existing literature, but rather to critically explore a theme where our understanding is still under development.

The search for papers revealed 450 articles, out of which 93¹⁰10 Liang M, Gao L, Cheng C, Zhou Q, Uy JP, Heiner K, Sun C. Efficacy of face mask in preventing respiratory virus transmission: A systematic review and meta-analysis. Travel Med Infect Dis 2020; 36:101751.^,2020 Wang M-W, Zhou M-Y, Ji G-H, Ye L, Cheng Y-R, Feng Z-H, Chen J. Mask crisis during the COVID-19 outbreak. Eur Rev Med Pharmacol Sci 2020; 24(6):3397-3399.^,2121 Feng S, Shen C, Xia N, Song W, Fan M, Cowling BJ. Rational use of face masks in the COVID-19 pandemic. Lancet Respir Med 2020; 8(5):434-436.^,2626 Leung CC, Lam TH, Cheng KK. Let us not forget the mask in our attempts to stall the spread of COVID-19. Int J Tuberc Lung Dis 2020; 24(4):364-366.

27 Zhong B-L, Luo W, Li H-M, Zhang Q-Q, Liu X-G, Li W-T, Li Y. Knowledge, attitudes, and practices towards COVID-19 among Chinese residents during the rapid rise period of the COVID-19 outbreak: a quick online cross-sectional survey. Int J Biol Sci 2020; 16(10):1745-1752.

28 Adhikari SP, Meng S, Wu Y-J, Mao Y-P, Ye R-X, Wang Q-Z, Sun C, Sylvia S, Rozelle S, Raat H, Zhou H. Epidemiology, causes, clinical manifestation and diagnosis, prevention and control of coronavirus disease (COVID-19) during the early outbreak period: a scoping review. Infect Dis Poverty 2020; 9(1):29.

29 Leung CC, Lam TH, Cheng KK. Mass masking in the COVID-19 epidemic: people need guidance. Lancet 2020; 395(10228):945.

30 Zhai Z. Facial mask: A necessity to beat COVID-19. Build Environ 2020; 175:106827.

31 Liu X, Zhang S. COVID-19: Face masks and human-to-human transmission. Influenza Other Respi Viruses 2020; 14(4):472-473 .

32 Ma Q-X, Shan H, Zhang H-L, Li G-M, Yang R-M, Chen J-M. Potential utilities of mask-wearing and instant hand hygiene for fighting SARS-CoV-2. J Med Virol 2020; 92(9):1567-1571.

33 Worby CJ, Chang H-H. Face mask use in the general population and optimal resource allocation during the COVID-19 pandemic. Nat Commun 2020; 11(1):4049.

34 Zhou Z-G, Yue D-S, Mu C-L, Zhang L. Mask is the possible key for self-isolation in COVID-19 pandemic. J Med Virol 2020; 10.1002/jmv.25846.
https://doi.org/10.1002/jmv.25846...

35 Javid B, Weekes MP, Matheson NJ. Covid-19: should the public wear face masks? BMJ 2020; 369:m1442.

36 Greenhalgh T, Schmid MB, Czypionka T, Bassler D, Gruer L. Face masks for the public during the covid-19 crisis. BMJ 2020; 369:m1435.

37 Wang M-W, Cheng Y-R, Ye L, Zhou M-Y, Chen J, Feng Z-H. The COVID-19 outbreak: The issue of face masks. Infect Control Hosp Epidemiol 2020; 41(8):974-975.

38 Han G, Zhou Y-H. Possibly critical role of wearing masks in general population in controlling COVID-19. J Med Virol 2020; 10.1002/jmv.25886.
https://doi.org/10.1002/jmv.25886...

39 Gandhi M, Havlir D. The Time for Universal Masking of the Public for Coronavirus Disease 2019 Is Now. Open Forum Infect Dis 2020; 7(4):ofaa131.

40 Cheng KK, Lam TH, Leung CC. Wearing face masks in the community during the COVID-19 pandemic: altruism and solidarity. Lancet 2020; S0140-6736(20)30918-1 .

41 Pleil JD, Beauchamp JD, Risby TH, Dweik RA. The scientific rationale for the use of simple masks or improvised facial coverings to trap exhaled aerosols and possibly reduce the breathborne spread of COVID-19. J Breath Res 2020; 14(3):030201.

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43 Desai AN, Aronoff DM. Masks and Coronavirus Disease 2019 (COVID-19). JAMA 2020; 323(20):2103.

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51 Cho-Han Chiang, Cho-Hung Chiang, Cho-Hsien Chiang, Yee-Chun Chen. The Practice of Wearing Surgical Masks during the COVID-19 Pandemic. Emerg Infect Dis 2020; 26(8):1962.

52 Setti L, Passarini F, De Gennaro G, Barbieri P, Perrone MG, Borelli M, Palmisani J, Di Gilio A, Piscitelli P, Miani A. Airborne Transmission Route of COVID-19: Why 2 Meters/6 Feet of Inter-Personal Distance Could Not Be Enough. Int J Environ Res Public Health 2020; 17(8):2932.

53 Cheng VCC, Wong S-C, Chuang VWM, So SY-C, Chen JH-K, Sridhar S, To KK-W, Chan JF-W, Hung IF-N, Ho P-L, Yuen K-Y. The role of community-wide wearing of face mask for control of coronavirus disease 2019 (COVID-19) epidemic due to SARS-CoV-2. J Infect 2020; 81(1):107-114.

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56 Wu E, Qi D. Masks and thermometers: Paramount measures to stop the rapid spread of SARS-CoV-2 in the United States. Genes Dis 2020; 10.1016/j.gendis.2020.04.011.
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60 MacIntyre CR, Chughtai AA. A rapid systematic review of the efficacy of face masks and respirators against coronaviruses and other respiratory transmissible viruses for the community, healthcare workers and sick patients. Int J Nurs Stud 2020; 108:103629.

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63 Kang Y-J. Lessons Learned From Cases of COVID-19 Infection in South Korea. Disaster Med Public Health Prep 2020; 1-8.

64 Clements JM. Knowledge and Behaviors Toward COVID-19 Among US Residents During the Early Days of the Pandemic: Cross-Sectional Online Questionnaire. JMIR Public Health Surveill 2020; 6(2):e19161.

65 Esposito S, Principi N. To mask or not to mask children to overcome COVID-19. Eur J Pediatr 2020; 179(8):1267-1270.

66 Parry J. Covid-19: Hong Kong government supplies reusable face masks to all residents. BMJ 2020; 369:m1880.

67 Soto DM, Cardona Maya WD, Agudelo EL, Bueno-Sánchez JC. The feasibility of generalized face mask usage during the COVID-19 pandemic: a perspective from Latin America. Infect Control Hosp Epidemiol 2020; 1-2.

68 Huang Y, Wu Q, Wang P, Xu Y, Wang L, Zhao Y, Yao D, Xu Y, Lv Q, Xu S. Measures Undertaken in China to Avoid COVID-19 Infection: Internet-Based, Cross-Sectional Survey Study. J Med Internet Res 2020; 22(5):e18718.

69 Sra HK, Sandhu A, Singh M. Use of Face Masks in COVID-19. Indian J Pediatr 2020; 87:553.

70 Kashyap A, Singh K, Sabat D, Maini L. Fast and economic cardboard cutout use to increase compliance of face mask wear during COVID-19 pandemic. J Clin Orthop Trauma 2020; 11(Supl. 3):S298-S300.

71 Matusiak L, Szepietowska M, Krajewski P, Bialynicki-Birula R, Szepietowski JC. Inconveniences due to the use of face masks during the COVID-19 pandemic: A survey study of 876 young people. Dermatol Ther 2020; 33(4):e13567.

72 Ogoina D. COVID-19: The Need for Rational Use of Face Masks in Nigeria. Am J Trop Med Hyg 2020; 103(1):33-34.

73 Feng Y, Marchal T, Sperry T, Yi H. Influence of wind and relative humidity on the social distancing effectiveness to prevent COVID-19 airborne transmission: A numerical study. J Aerosol Sci 2020; 105585.

74 Noh JY, Seong H, Yoon JG, Song JY, Cheong HJ, Kim WJ. Social Distancing against COVID-19: Implication for the Control of Influenza. J Korean Med Sci 2020; 35(19):e182.

75 Gao Q, Hu Y, Dai Z, Xiao F, Wang J, Wu J. The epidemiological characteristics of 2019 novel coronavirus diseases (COVID-19) in Jingmen, Hubei, China. Medicine 2020; 99(23):e20605.

76 Clase CM, Fu EL, Joseph M, Beale RCL, Dolovich MB, Jardine M, Mann JFE, Pecoits-Filho R, Winkelmayer WC, Carrero JJ. Cloth Masks May Prevent Transmission of COVID-19: An Evidence-Based, Risk-Based Approach. Ann Intern Med 2020; 173(6):489-491 .

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98 Szarpak L, Smereka J, Filipiak KJ, Ladny JR, Jaguszewski M. Cloth masks versus medical masks for COVID-19 protection. Cardiol J 2020; 27(2):218-219.

99 Lazcano-Ponce E, Alpuche-Aranda C. Public health literacy in the face of the Covid-19 pandemic emergency. Salud Publica Mex 2020; 62(3):331-340.

100 Martin GP, Hanna E, Dingwall R. Urgency and uncertainty: covid-19, face masks, and evidence informed policy. BMJ 2020; 369:m2017.

101 Wu H-L, Huang J, Zhang CJP, He Z, Ming W-K. Facemask shortage and the novel coronavirus disease (COVID-19) outbreak: Reflections on public health measures. EClinicalMedicine 2020; 21:100329.

102 Stone TE, Kunaviktikul W, Omura M, Petrini M. Editorial: Facemasks and the Covid 19 pandemic: What advice should health professionals be giving the general public about the wearing of facemasks? Nurs Health Sci 2020; 22(2):339-342.

103 Chowdhury A, Jahan N, Wang S. One month of the novel coronavirus 2019 outbreak: Is it still a threat? Virusdisease 2020; 31(2):1-5.

104 Amendola L, Saurini MT, Di Girolamo F, Arduini F. A rapid screening method for testing the efficiency of masks in breaking down aerosols. Microchem J 2020; 157:104928.

105 Kim MN. What Type of Face Mask Is Appropriate for Everyone-Mask-Wearing Policy amidst COVID-19 Pandemic? J Korean Med Sci 2020; 35(20):e186.

106 Lam SKK, Hung MSY, Chien WT. Uncertainty surrounding the use of face masks in the community amid the COVID-19 pandemic. Int J Nurs Stud 2020; 108:103651.

107 King FM. Covid-19: face masks could foster distrust and blame. BMJ 2020; 369:m2009.

108 Cheng S-T. Covid-19: are face masks a good long term strategy? BMJ 2020; 369:m2005.

109 Lazzarino AI, Steptoe A, Hamer M, Michie S. Covid-19: Important potential side effects of wearing face masks that we should bear in mind. BMJ 2020; 369:m2003.

110 Schroter RC. Social distancing for covid-19: is 2 metres far enough? BMJ 2020; 369:m2010.

111 Azlan AA, Hamzah MR, Sern TJ, Ayub SH, Mohamad E. Public knowledge, attitudes and practices towards COVID-19: A cross-sectional study in Malaysia. PLoS One 2020; 15(5):e0233668.

112 Szepietowski JC, Matusiak L, Szepietowska M, Krajewski PK, Bialynicki-Birula R. Face Mask-induced Itch: A Self-questionnaire Study of 2,315 Responders During the COVID-19 Pandemic. Acta Derm Venereol 2020; 100:adv00152.

113 Aggarwal N, Dwarakanathan V, Gautam N, Ray A. Facemasks for prevention of viral respiratory infections in community settings: A systematic review and meta-analysis. Indian J Public Health 2020; 64(Supl.):S192-S200.

114 Zhao M, Liao L, Xiao W, Yu X, Wang H, Wang Q, Lin YL, Kilinc-Balci FS, Price A, Chu L, Chu MC, Chu S, Cui Y. Household Materials Selection for Homemade Cloth Face Coverings and Their Filtration Efficiency Enhancement with Triboelectric Charging. Nano Lett 2020; 20(7):5544-5552.^-115115 Filho C, Vieira LJES, Silva RM. Buscas na internet sobre medidas de enfrentamento à COVID-19 no Brasil: descrição de pesquisas realizadas nos primeiros 100 dias de 2020. Epidemiol Serv Saúde 2020; 29(3):e2020191. met selection criteria and were included in this review (Figure 1).

The manuscripts selected were classified according to the month and type of scientific publication (Figure 2). Within the period studied, April (n=33)^{33-37,39-47,49-60,97-99,102,103,115} and May (n=35)¹⁰10 Liang M, Gao L, Cheng C, Zhou Q, Uy JP, Heiner K, Sun C. Efficacy of face mask in preventing respiratory virus transmission: A systematic review and meta-analysis. Travel Med Infect Dis 2020; 36:101751.^,4242 Cowling BJ, Ali ST, Ng TWY, Tsang TK, Li JCM, Fong MW, Liao Q, Kwan MY, Lee SL, Chiu SS, Wu JT, Wu P, Leung GM. Impact assessment of non-pharmaceutical interventions against coronavirus disease 2019 and influenza in Hong Kong: an observational study. Lancet Public Health 2020; ;5(5):e279-e288 .^,6161 Hoertel N, Blachier M, Blanco C, Olfson M, Massetti M, Rico MS, Limosin F, Leleu H. Lockdown exit strategies and risk of a second epidemic peak: a stochastic agent-based model of SARS-CoV-2 epidemic in France. medRxiv 2020; 10.1101/2020.04.30.20086264.
https://doi.org/10.1101/2020.04.30.20086...

62 Szczesniak D, Ciulkowicz M, Maciaszek J, Misiak B, Luc D, Wieczorek T, Witecka K-F, Rymaszewska J. Psychopathological responses and face mask restrictions during the COVID-19 outbreak: Results from a nationwide survey. Brain Behav Immun 2020; 87:161-162.

63 Kang Y-J. Lessons Learned From Cases of COVID-19 Infection in South Korea. Disaster Med Public Health Prep 2020; 1-8.

64 Clements JM. Knowledge and Behaviors Toward COVID-19 Among US Residents During the Early Days of the Pandemic: Cross-Sectional Online Questionnaire. JMIR Public Health Surveill 2020; 6(2):e19161.

65 Esposito S, Principi N. To mask or not to mask children to overcome COVID-19. Eur J Pediatr 2020; 179(8):1267-1270.

66 Parry J. Covid-19: Hong Kong government supplies reusable face masks to all residents. BMJ 2020; 369:m1880.

67 Soto DM, Cardona Maya WD, Agudelo EL, Bueno-Sánchez JC. The feasibility of generalized face mask usage during the COVID-19 pandemic: a perspective from Latin America. Infect Control Hosp Epidemiol 2020; 1-2.

68 Huang Y, Wu Q, Wang P, Xu Y, Wang L, Zhao Y, Yao D, Xu Y, Lv Q, Xu S. Measures Undertaken in China to Avoid COVID-19 Infection: Internet-Based, Cross-Sectional Survey Study. J Med Internet Res 2020; 22(5):e18718.

69 Sra HK, Sandhu A, Singh M. Use of Face Masks in COVID-19. Indian J Pediatr 2020; 87:553.

70 Kashyap A, Singh K, Sabat D, Maini L. Fast and economic cardboard cutout use to increase compliance of face mask wear during COVID-19 pandemic. J Clin Orthop Trauma 2020; 11(Supl. 3):S298-S300.

71 Matusiak L, Szepietowska M, Krajewski P, Bialynicki-Birula R, Szepietowski JC. Inconveniences due to the use of face masks during the COVID-19 pandemic: A survey study of 876 young people. Dermatol Ther 2020; 33(4):e13567.

72 Ogoina D. COVID-19: The Need for Rational Use of Face Masks in Nigeria. Am J Trop Med Hyg 2020; 103(1):33-34.

73 Feng Y, Marchal T, Sperry T, Yi H. Influence of wind and relative humidity on the social distancing effectiveness to prevent COVID-19 airborne transmission: A numerical study. J Aerosol Sci 2020; 105585.

74 Noh JY, Seong H, Yoon JG, Song JY, Cheong HJ, Kim WJ. Social Distancing against COVID-19: Implication for the Control of Influenza. J Korean Med Sci 2020; 35(19):e182.

75 Gao Q, Hu Y, Dai Z, Xiao F, Wang J, Wu J. The epidemiological characteristics of 2019 novel coronavirus diseases (COVID-19) in Jingmen, Hubei, China. Medicine 2020; 99(23):e20605.

76 Clase CM, Fu EL, Joseph M, Beale RCL, Dolovich MB, Jardine M, Mann JFE, Pecoits-Filho R, Winkelmayer WC, Carrero JJ. Cloth Masks May Prevent Transmission of COVID-19: An Evidence-Based, Risk-Based Approach. Ann Intern Med 2020; 173(6):489-491 .

77 Chiang C-H, Chiang C-H, Chiang C-H. Letter to editor - Can universal masking help with our recovery from the COVID-19 pandemic? Int J Surg 2020; 79:125-126.

78 Goscé L, Phillips PA, Spinola P, Gupta DRK, Abubakar PI. Modelling SARS-COV2 Spread in London: Approaches to Lift the Lockdown. J Infect 2020; 81(2):260-265.

79 Middleton JD, Lopes H. Face masks in the covid-19 crisis: caveats, limits, and priorities. BMJ 2020; 369:m2030.

80 Laestadius L, Wang Y, Ben Taleb Z, Kalan ME, Cho Y, Manganello J. Online National Health Agency Mask Guidance for the Public in Light of COVID-19: Content Analysis. JMIR Public Health Surveill 2020; 6(2):e19501

81 Majeed A, Seo Y, Heo K, Lee D. Can the UK emulate the South Korean approach to covid-19? BMJ 2020; 369:m2084.^-8282 Chan EYY, Huang Z, Lo ESK, Hung KKC, Wong ELY, Wong SYS. Sociodemographic Predictors of Health Risk Perception, Attitude and Behavior Practices Associated with Health-Emergency Disaster Risk Management for Biological Hazards: The Case of COVID-19 Pandemic in Hong Kong, SAR China. Int J Environ Res Public Health 2020; 17(11):3869.^,8484 Liu X, Luo W-T, Li Y, Li C-N, Hong Z-S, Chen H-L, Xiao F, Xia J-Y. Psychological status and behavior changes of the public during the COVID-19 epidemic in China. Infect Dis Poverty 2020; 9(1):58.^,100100 Martin GP, Hanna E, Dingwall R. Urgency and uncertainty: covid-19, face masks, and evidence informed policy. BMJ 2020; 369:m2017.^,104104 Amendola L, Saurini MT, Di Girolamo F, Arduini F. A rapid screening method for testing the efficiency of masks in breaking down aerosols. Microchem J 2020; 157:104928.

105 Kim MN. What Type of Face Mask Is Appropriate for Everyone-Mask-Wearing Policy amidst COVID-19 Pandemic? J Korean Med Sci 2020; 35(20):e186.

106 Lam SKK, Hung MSY, Chien WT. Uncertainty surrounding the use of face masks in the community amid the COVID-19 pandemic. Int J Nurs Stud 2020; 108:103651.

107 King FM. Covid-19: face masks could foster distrust and blame. BMJ 2020; 369:m2009.

108 Cheng S-T. Covid-19: are face masks a good long term strategy? BMJ 2020; 369:m2005.

109 Lazzarino AI, Steptoe A, Hamer M, Michie S. Covid-19: Important potential side effects of wearing face masks that we should bear in mind. BMJ 2020; 369:m2003.

110 Schroter RC. Social distancing for covid-19: is 2 metres far enough? BMJ 2020; 369:m2010.

111 Azlan AA, Hamzah MR, Sern TJ, Ayub SH, Mohamad E. Public knowledge, attitudes and practices towards COVID-19: A cross-sectional study in Malaysia. PLoS One 2020; 15(5):e0233668.^-112112 Szepietowski JC, Matusiak L, Szepietowska M, Krajewski PK, Bialynicki-Birula R. Face Mask-induced Itch: A Self-questionnaire Study of 2,315 Responders During the COVID-19 Pandemic. Acta Derm Venereol 2020; 100:adv00152.^,116116 Han C, Shi J, Chen Y, Zhang Z. Increased flare of acne caused by long-time mask wearing during COVID -19 pandemic among general population. Dermatol Ther 2020; 33(4):e13704. had the highest number of publications. Opinion pieces, editorials and commentaries were predominant up to April (n=25), after which cross-sectional and modeling studies began to prevail (Figure 2). Of the manuscripts analyzed, 49,5% were opinion pieces, commentary, letters and editorials; 34,4% were transversal studies; and 16,1% were literature reviews metanalysis¹⁰10 Liang M, Gao L, Cheng C, Zhou Q, Uy JP, Heiner K, Sun C. Efficacy of face mask in preventing respiratory virus transmission: A systematic review and meta-analysis. Travel Med Infect Dis 2020; 36:101751.^,2828 Adhikari SP, Meng S, Wu Y-J, Mao Y-P, Ye R-X, Wang Q-Z, Sun C, Sylvia S, Rozelle S, Raat H, Zhou H. Epidemiology, causes, clinical manifestation and diagnosis, prevention and control of coronavirus disease (COVID-19) during the early outbreak period: a scoping review. Infect Dis Poverty 2020; 9(1):29.^,3939 Gandhi M, Havlir D. The Time for Universal Masking of the Public for Coronavirus Disease 2019 Is Now. Open Forum Infect Dis 2020; 7(4):ofaa131.^,4545 Abd-Elsayed A, Karri J. Utility of Substandard Face Mask Options for Health Care Workers During the COVID-19 Pandemic. Anesth Analg; 131(1):4-6 .^,6060 MacIntyre CR, Chughtai AA. A rapid systematic review of the efficacy of face masks and respirators against coronaviruses and other respiratory transmissible viruses for the community, healthcare workers and sick patients. Int J Nurs Stud 2020; 108:103629.^,6565 Esposito S, Principi N. To mask or not to mask children to overcome COVID-19. Eur J Pediatr 2020; 179(8):1267-1270.^,7676 Clase CM, Fu EL, Joseph M, Beale RCL, Dolovich MB, Jardine M, Mann JFE, Pecoits-Filho R, Winkelmayer WC, Carrero JJ. Cloth Masks May Prevent Transmission of COVID-19: An Evidence-Based, Risk-Based Approach. Ann Intern Med 2020; 173(6):489-491 .^,8686 Chu DK, Akl EA, Duda S, Solo K, Yaacoub S, Schünemann HJ, COVID-19 Systematic Urgent Review Group Effort (SURGE) study authors. Physical distancing, face masks, and eye protection to prevent person-to-person transmission of SARS-CoV-2 and COVID-19: a systematic review and meta-analysis. Lancet 2020; 395(10242):1973-1987^,8989 Li DTS, Samaranayake LP, Leung YY, Neelakantan P. Facial protection in the era of COVID-19: A narrative review. Oral Dis 2020; 10.1111/odi.13460.
https://doi.org/10.1111/odi.13460... ^,9090 Goh Y, Tan BYQ, Bhartendu C, Ong JJY, Sharma VK. The face mask: How a real protection becomes a psychological symbol during Covid-19? Brain Behav Immun 2020; 88:1-5.^,9595 Esposito S, Principi N, Leung CC, Migliori GB. Universal use of face masks for success against COVID-19: evidence and implications for prevention policies. Eur Respir J 2020; 55(6):2001260.^,101101 Wu H-L, Huang J, Zhang CJP, He Z, Ming W-K. Facemask shortage and the novel coronavirus disease (COVID-19) outbreak: Reflections on public health measures. EClinicalMedicine 2020; 21:100329.^,103103 Chowdhury A, Jahan N, Wang S. One month of the novel coronavirus 2019 outbreak: Is it still a threat? Virusdisease 2020; 31(2):1-5.^,105105 Kim MN. What Type of Face Mask Is Appropriate for Everyone-Mask-Wearing Policy amidst COVID-19 Pandemic? J Korean Med Sci 2020; 35(20):e186.^,113113 Aggarwal N, Dwarakanathan V, Gautam N, Ray A. Facemasks for prevention of viral respiratory infections in community settings: A systematic review and meta-analysis. Indian J Public Health 2020; 64(Supl.):S192-S200. (Figure 2).

The papers were also classified with respect to their position on the widespread use of cloth masks (Figure 3). Of the scientific papers included (n=93), 77.4% (n=72) were favorable to the widespread use of cloth masks in face of the COVID-19 pandemic¹⁰10 Liang M, Gao L, Cheng C, Zhou Q, Uy JP, Heiner K, Sun C. Efficacy of face mask in preventing respiratory virus transmission: A systematic review and meta-analysis. Travel Med Infect Dis 2020; 36:101751.^,2626 Leung CC, Lam TH, Cheng KK. Let us not forget the mask in our attempts to stall the spread of COVID-19. Int J Tuberc Lung Dis 2020; 24(4):364-366.

27 Zhong B-L, Luo W, Li H-M, Zhang Q-Q, Liu X-G, Li W-T, Li Y. Knowledge, attitudes, and practices towards COVID-19 among Chinese residents during the rapid rise period of the COVID-19 outbreak: a quick online cross-sectional survey. Int J Biol Sci 2020; 16(10):1745-1752.

28 Adhikari SP, Meng S, Wu Y-J, Mao Y-P, Ye R-X, Wang Q-Z, Sun C, Sylvia S, Rozelle S, Raat H, Zhou H. Epidemiology, causes, clinical manifestation and diagnosis, prevention and control of coronavirus disease (COVID-19) during the early outbreak period: a scoping review. Infect Dis Poverty 2020; 9(1):29.

29 Leung CC, Lam TH, Cheng KK. Mass masking in the COVID-19 epidemic: people need guidance. Lancet 2020; 395(10228):945.

30 Zhai Z. Facial mask: A necessity to beat COVID-19. Build Environ 2020; 175:106827.

31 Liu X, Zhang S. COVID-19: Face masks and human-to-human transmission. Influenza Other Respi Viruses 2020; 14(4):472-473 .

32 Ma Q-X, Shan H, Zhang H-L, Li G-M, Yang R-M, Chen J-M. Potential utilities of mask-wearing and instant hand hygiene for fighting SARS-CoV-2. J Med Virol 2020; 92(9):1567-1571.

33 Worby CJ, Chang H-H. Face mask use in the general population and optimal resource allocation during the COVID-19 pandemic. Nat Commun 2020; 11(1):4049.

34 Zhou Z-G, Yue D-S, Mu C-L, Zhang L. Mask is the possible key for self-isolation in COVID-19 pandemic. J Med Virol 2020; 10.1002/jmv.25846.
https://doi.org/10.1002/jmv.25846...

35 Javid B, Weekes MP, Matheson NJ. Covid-19: should the public wear face masks? BMJ 2020; 369:m1442.

36 Greenhalgh T, Schmid MB, Czypionka T, Bassler D, Gruer L. Face masks for the public during the covid-19 crisis. BMJ 2020; 369:m1435.

37 Wang M-W, Cheng Y-R, Ye L, Zhou M-Y, Chen J, Feng Z-H. The COVID-19 outbreak: The issue of face masks. Infect Control Hosp Epidemiol 2020; 41(8):974-975.

38 Han G, Zhou Y-H. Possibly critical role of wearing masks in general population in controlling COVID-19. J Med Virol 2020; 10.1002/jmv.25886.
https://doi.org/10.1002/jmv.25886...

39 Gandhi M, Havlir D. The Time for Universal Masking of the Public for Coronavirus Disease 2019 Is Now. Open Forum Infect Dis 2020; 7(4):ofaa131.

40 Cheng KK, Lam TH, Leung CC. Wearing face masks in the community during the COVID-19 pandemic: altruism and solidarity. Lancet 2020; S0140-6736(20)30918-1 .

41 Pleil JD, Beauchamp JD, Risby TH, Dweik RA. The scientific rationale for the use of simple masks or improvised facial coverings to trap exhaled aerosols and possibly reduce the breathborne spread of COVID-19. J Breath Res 2020; 14(3):030201.

42 Cowling BJ, Ali ST, Ng TWY, Tsang TK, Li JCM, Fong MW, Liao Q, Kwan MY, Lee SL, Chiu SS, Wu JT, Wu P, Leung GM. Impact assessment of non-pharmaceutical interventions against coronavirus disease 2019 and influenza in Hong Kong: an observational study. Lancet Public Health 2020; ;5(5):e279-e288 .

43 Desai AN, Aronoff DM. Masks and Coronavirus Disease 2019 (COVID-19). JAMA 2020; 323(20):2103.

44 MacIntyre CR, Hasanain SJ. Community Universal Face Mask Use during the COVID 19 pandemic-from households to travelers and public spaces. J Travel Med 2020; 27(3):taaa056.

45 Abd-Elsayed A, Karri J. Utility of Substandard Face Mask Options for Health Care Workers During the COVID-19 Pandemic. Anesth Analg; 131(1):4-6 .

46 Eikenberry SE, Mancuso M, Iboi E, Phan T, Eikenberry K, Kuang Y, Kostelich E, Gumel AB. To mask or not to mask: Modeling the potential for face mask use by the general public to curtail the COVID-19 pandemic. Infect Dis Model 2020; 5:293-308.

47 Thomson GA. COVID-19: Leaving lockdown-Of Schrodinger, cats, testing and masks. Int J Clin Pract 2020; 74(8):e13519.

48 Garcia LP. Use of facemasks to limit COVID-19 transmission. Epidemiol Serv Saude 2020; 29(2):e2020023.

49 Chen X, Ran L, Liu Q, Hu Q, Du X, Tan X. Hand Hygiene, Mask-Wearing Behaviors and Its Associated Factors during the COVID-19 Epidemic: A Cross-Sectional Study among Primary School Students in Wuhan, China. Int J Environ Res Public Health 2020; 17(8):2893.

50 Lee M, You M. Psychological and Behavioral Responses in South Korea During the Early Stages of Coronavirus Disease 2019 (COVID-19). Int J Environ Res Public Health 2020; 17(9):2977.

51 Cho-Han Chiang, Cho-Hung Chiang, Cho-Hsien Chiang, Yee-Chun Chen. The Practice of Wearing Surgical Masks during the COVID-19 Pandemic. Emerg Infect Dis 2020; 26(8):1962.

52 Setti L, Passarini F, De Gennaro G, Barbieri P, Perrone MG, Borelli M, Palmisani J, Di Gilio A, Piscitelli P, Miani A. Airborne Transmission Route of COVID-19: Why 2 Meters/6 Feet of Inter-Personal Distance Could Not Be Enough. Int J Environ Res Public Health 2020; 17(8):2932.

53 Cheng VCC, Wong S-C, Chuang VWM, So SY-C, Chen JH-K, Sridhar S, To KK-W, Chan JF-W, Hung IF-N, Ho P-L, Yuen K-Y. The role of community-wide wearing of face mask for control of coronavirus disease 2019 (COVID-19) epidemic due to SARS-CoV-2. J Infect 2020; 81(1):107-114.

54 Konda A, Prakash A, Moss GA, Schmoldt M, Grant GD, Guha S. Aerosol Filtration Efficiency of Common Fabrics Used in Respiratory Cloth Masks. ACS Nano 2020; 14(5):6339-6347.

55 Victor CWT, Shing YT, Wai KP, Helen KWL, Shara WYL. A reality check on the use of face masks during the COVID-19 outbreak in Hong Kong. EClinicalMedicine 2020; 22:100356.

56 Wu E, Qi D. Masks and thermometers: Paramount measures to stop the rapid spread of SARS-CoV-2 in the United States. Genes Dis 2020; 10.1016/j.gendis.2020.04.011.
https://doi.org/10.1016/j.gendis.2020.04...

57 Wilson AM, Abney SE, King M-F, Weir MH, López-García M, Sexton JD, Dancer SJ, Proctor J, Noakes CJ, Reynolds KA. COVID-19 and non-traditional mask use: How do various materials compare in reducing the infection risk for mask wearers? J Hosp Infect 2020; 105(4):640-642.

58 Sunjaya AP, Jenkins C. Rationale for universal face masks in public against COVID-19. Respirology 2020; 5(7):678-679.

59 Ngonghala CN, Iboi E, Eikenberry S, Scotch M, MacIntyre CR, Bonds MH, Gumel AB. Mathematical assessment of the impact of non-pharmaceutical interventions on curtailing the 2019 novel Coronavirus. Math Biosci 2020; 325:108364.

60 MacIntyre CR, Chughtai AA. A rapid systematic review of the efficacy of face masks and respirators against coronaviruses and other respiratory transmissible viruses for the community, healthcare workers and sick patients. Int J Nurs Stud 2020; 108:103629.

61 Hoertel N, Blachier M, Blanco C, Olfson M, Massetti M, Rico MS, Limosin F, Leleu H. Lockdown exit strategies and risk of a second epidemic peak: a stochastic agent-based model of SARS-CoV-2 epidemic in France. medRxiv 2020; 10.1101/2020.04.30.20086264.
https://doi.org/10.1101/2020.04.30.20086...

62 Szczesniak D, Ciulkowicz M, Maciaszek J, Misiak B, Luc D, Wieczorek T, Witecka K-F, Rymaszewska J. Psychopathological responses and face mask restrictions during the COVID-19 outbreak: Results from a nationwide survey. Brain Behav Immun 2020; 87:161-162.

63 Kang Y-J. Lessons Learned From Cases of COVID-19 Infection in South Korea. Disaster Med Public Health Prep 2020; 1-8.

64 Clements JM. Knowledge and Behaviors Toward COVID-19 Among US Residents During the Early Days of the Pandemic: Cross-Sectional Online Questionnaire. JMIR Public Health Surveill 2020; 6(2):e19161.

65 Esposito S, Principi N. To mask or not to mask children to overcome COVID-19. Eur J Pediatr 2020; 179(8):1267-1270.

66 Parry J. Covid-19: Hong Kong government supplies reusable face masks to all residents. BMJ 2020; 369:m1880.

67 Soto DM, Cardona Maya WD, Agudelo EL, Bueno-Sánchez JC. The feasibility of generalized face mask usage during the COVID-19 pandemic: a perspective from Latin America. Infect Control Hosp Epidemiol 2020; 1-2.

68 Huang Y, Wu Q, Wang P, Xu Y, Wang L, Zhao Y, Yao D, Xu Y, Lv Q, Xu S. Measures Undertaken in China to Avoid COVID-19 Infection: Internet-Based, Cross-Sectional Survey Study. J Med Internet Res 2020; 22(5):e18718.

69 Sra HK, Sandhu A, Singh M. Use of Face Masks in COVID-19. Indian J Pediatr 2020; 87:553.

70 Kashyap A, Singh K, Sabat D, Maini L. Fast and economic cardboard cutout use to increase compliance of face mask wear during COVID-19 pandemic. J Clin Orthop Trauma 2020; 11(Supl. 3):S298-S300.

71 Matusiak L, Szepietowska M, Krajewski P, Bialynicki-Birula R, Szepietowski JC. Inconveniences due to the use of face masks during the COVID-19 pandemic: A survey study of 876 young people. Dermatol Ther 2020; 33(4):e13567.

72 Ogoina D. COVID-19: The Need for Rational Use of Face Masks in Nigeria. Am J Trop Med Hyg 2020; 103(1):33-34.

73 Feng Y, Marchal T, Sperry T, Yi H. Influence of wind and relative humidity on the social distancing effectiveness to prevent COVID-19 airborne transmission: A numerical study. J Aerosol Sci 2020; 105585.

74 Noh JY, Seong H, Yoon JG, Song JY, Cheong HJ, Kim WJ. Social Distancing against COVID-19: Implication for the Control of Influenza. J Korean Med Sci 2020; 35(19):e182.

75 Gao Q, Hu Y, Dai Z, Xiao F, Wang J, Wu J. The epidemiological characteristics of 2019 novel coronavirus diseases (COVID-19) in Jingmen, Hubei, China. Medicine 2020; 99(23):e20605.

76 Clase CM, Fu EL, Joseph M, Beale RCL, Dolovich MB, Jardine M, Mann JFE, Pecoits-Filho R, Winkelmayer WC, Carrero JJ. Cloth Masks May Prevent Transmission of COVID-19: An Evidence-Based, Risk-Based Approach. Ann Intern Med 2020; 173(6):489-491 .

77 Chiang C-H, Chiang C-H, Chiang C-H. Letter to editor - Can universal masking help with our recovery from the COVID-19 pandemic? Int J Surg 2020; 79:125-126.

78 Goscé L, Phillips PA, Spinola P, Gupta DRK, Abubakar PI. Modelling SARS-COV2 Spread in London: Approaches to Lift the Lockdown. J Infect 2020; 81(2):260-265.

79 Middleton JD, Lopes H. Face masks in the covid-19 crisis: caveats, limits, and priorities. BMJ 2020; 369:m2030.

80 Laestadius L, Wang Y, Ben Taleb Z, Kalan ME, Cho Y, Manganello J. Online National Health Agency Mask Guidance for the Public in Light of COVID-19: Content Analysis. JMIR Public Health Surveill 2020; 6(2):e19501

81 Majeed A, Seo Y, Heo K, Lee D. Can the UK emulate the South Korean approach to covid-19? BMJ 2020; 369:m2084.

82 Chan EYY, Huang Z, Lo ESK, Hung KKC, Wong ELY, Wong SYS. Sociodemographic Predictors of Health Risk Perception, Attitude and Behavior Practices Associated with Health-Emergency Disaster Risk Management for Biological Hazards: The Case of COVID-19 Pandemic in Hong Kong, SAR China. Int J Environ Res Public Health 2020; 17(11):3869.

83 Han C, Shi J, Chen Y, Zhang Z. Increased flare of acne caused by long-time mask wearing during COVID-19 pandemic among general population. Dermatol Ther 2020; 33(4):e13704.

84 Liu X, Luo W-T, Li Y, Li C-N, Hong Z-S, Chen H-L, Xiao F, Xia J-Y. Psychological status and behavior changes of the public during the COVID-19 epidemic in China. Infect Dis Poverty 2020; 9(1):58.

85 Lee H, Lee H, Song K-H, Kim ES, Park JS, Jung J, Ahn S, Jeong EK, Park H, Kim HB. Impact of Public Health Interventions on Seasonal Influenza Activity During the SARS-CoV-2 Outbreak in Korea. Clin Infect Dis 2020; ciaa672.

86 Chu DK, Akl EA, Duda S, Solo K, Yaacoub S, Schünemann HJ, COVID-19 Systematic Urgent Review Group Effort (SURGE) study authors. Physical distancing, face masks, and eye protection to prevent person-to-person transmission of SARS-CoV-2 and COVID-19: a systematic review and meta-analysis. Lancet 2020; 395(10242):1973-1987

87 Liu PL. COVID-19 Information Seeking on Digital Media and Preventive Behaviors: The Mediation Role of Worry. Cyberpsychol Behav Soc Netw 2020; 23(10):677-682.

88 Jung F, Krieger V, Hufert FT, Küpper J-H. How we should respond to the Coronavirus SARS-CoV-2 outbreak: A German perspective. Clin Hemorheol Microcirc 2020; 74(4):363-372.

89 Li DTS, Samaranayake LP, Leung YY, Neelakantan P. Facial protection in the era of COVID-19: A narrative review. Oral Dis 2020; 10.1111/odi.13460.
https://doi.org/10.1111/odi.13460...

90 Goh Y, Tan BYQ, Bhartendu C, Ong JJY, Sharma VK. The face mask: How a real protection becomes a psychological symbol during Covid-19? Brain Behav Immun 2020; 88:1-5.

91 Greenhalgh T. Laying straw men to rest: author's reply to 'Urgency and uncertainty: covid-19, face masks, and evidence informed policy'. BMJ 2020; 369:m2240

92 Wong LP, Alias H, Danaee M, Ziaee M, Abedi F, Ziaee A, Mohajer S, HajiAliBeigloo R, Nia MN, Jamei F, Mazlom SR. Uncovering psychobehavioral implications of SARS-CoV-2 infection in Iran. Transbound Emerg Dis 2020; 10.1111/tbed.13662.
https://doi.org/10.1111/tbed.13662...

93 Zhang R, Li Y, Zhang AL, Wang Y, Molina MJ. Identifying airborne transmission as the dominant route for the spread of COVID-19. Proc Natl Acad Sci USA 2020; 117(26):14857-14863.

94 Ho K-F, Lin L-Y, Weng S-P, Chuang K-J. Medical mask versus cotton mask for preventing respiratory droplet transmission in micro environments. Sci Total Environ 2020; 735:139510.

95 Esposito S, Principi N, Leung CC, Migliori GB. Universal use of face masks for success against COVID-19: evidence and implications for prevention policies. Eur Respir J 2020; 55(6):2001260.^-9696 Dkhar SA, Quansar R, Saleem SM, Khan SMS. Knowledge, attitude, and practices related to COVID-19 pandemic among social media users in J&K, India. Indian J Public Health 2020; 64(Supl.):S205-S210. and 4.3% (n=4)⁹⁷97 Mahase E. Covid-19: What is the evidence for cloth masks? BMJ 2020; 369:m1422.

98 Szarpak L, Smereka J, Filipiak KJ, Ladny JR, Jaguszewski M. Cloth masks versus medical masks for COVID-19 protection. Cardiol J 2020; 27(2):218-219.

99 Lazcano-Ponce E, Alpuche-Aranda C. Public health literacy in the face of the Covid-19 pandemic emergency. Salud Publica Mex 2020; 62(3):331-340.^-100100 Martin GP, Hanna E, Dingwall R. Urgency and uncertainty: covid-19, face masks, and evidence informed policy. BMJ 2020; 369:m2017. were against its usage. It is important to highlight that all the papers that were against the use of masks were opinion pieces, commentaries, letters or editorials. Among those that were in favor of the widespread use of cloth masks were transversal studies (n=28)¹⁸18 Ma QX, Shan H, Zhang HL, Li GM. Potential utilities of mask-wearing and instant hand hygiene for fighting SARS-CoV-2. J Med Virol 2020; 92(9):1567-1571.^,2727 Zhong B-L, Luo W, Li H-M, Zhang Q-Q, Liu X-G, Li W-T, Li Y. Knowledge, attitudes, and practices towards COVID-19 among Chinese residents during the rapid rise period of the COVID-19 outbreak: a quick online cross-sectional survey. Int J Biol Sci 2020; 16(10):1745-1752.^,3333 Worby CJ, Chang H-H. Face mask use in the general population and optimal resource allocation during the COVID-19 pandemic. Nat Commun 2020; 11(1):4049.^,4242 Cowling BJ, Ali ST, Ng TWY, Tsang TK, Li JCM, Fong MW, Liao Q, Kwan MY, Lee SL, Chiu SS, Wu JT, Wu P, Leung GM. Impact assessment of non-pharmaceutical interventions against coronavirus disease 2019 and influenza in Hong Kong: an observational study. Lancet Public Health 2020; ;5(5):e279-e288 .^,4646 Eikenberry SE, Mancuso M, Iboi E, Phan T, Eikenberry K, Kuang Y, Kostelich E, Gumel AB. To mask or not to mask: Modeling the potential for face mask use by the general public to curtail the COVID-19 pandemic. Infect Dis Model 2020; 5:293-308.^,4949 Chen X, Ran L, Liu Q, Hu Q, Du X, Tan X. Hand Hygiene, Mask-Wearing Behaviors and Its Associated Factors during the COVID-19 Epidemic: A Cross-Sectional Study among Primary School Students in Wuhan, China. Int J Environ Res Public Health 2020; 17(8):2893.^,5050 Lee M, You M. Psychological and Behavioral Responses in South Korea During the Early Stages of Coronavirus Disease 2019 (COVID-19). Int J Environ Res Public Health 2020; 17(9):2977.^,5353 Cheng VCC, Wong S-C, Chuang VWM, So SY-C, Chen JH-K, Sridhar S, To KK-W, Chan JF-W, Hung IF-N, Ho P-L, Yuen K-Y. The role of community-wide wearing of face mask for control of coronavirus disease 2019 (COVID-19) epidemic due to SARS-CoV-2. J Infect 2020; 81(1):107-114.

54 Konda A, Prakash A, Moss GA, Schmoldt M, Grant GD, Guha S. Aerosol Filtration Efficiency of Common Fabrics Used in Respiratory Cloth Masks. ACS Nano 2020; 14(5):6339-6347.^-5555 Victor CWT, Shing YT, Wai KP, Helen KWL, Shara WYL. A reality check on the use of face masks during the COVID-19 outbreak in Hong Kong. EClinicalMedicine 2020; 22:100356.^,5757 Wilson AM, Abney SE, King M-F, Weir MH, López-García M, Sexton JD, Dancer SJ, Proctor J, Noakes CJ, Reynolds KA. COVID-19 and non-traditional mask use: How do various materials compare in reducing the infection risk for mask wearers? J Hosp Infect 2020; 105(4):640-642.^,5959 Ngonghala CN, Iboi E, Eikenberry S, Scotch M, MacIntyre CR, Bonds MH, Gumel AB. Mathematical assessment of the impact of non-pharmaceutical interventions on curtailing the 2019 novel Coronavirus. Math Biosci 2020; 325:108364.^,6161 Hoertel N, Blachier M, Blanco C, Olfson M, Massetti M, Rico MS, Limosin F, Leleu H. Lockdown exit strategies and risk of a second epidemic peak: a stochastic agent-based model of SARS-CoV-2 epidemic in France. medRxiv 2020; 10.1101/2020.04.30.20086264.
https://doi.org/10.1101/2020.04.30.20086... ^,6363 Kang Y-J. Lessons Learned From Cases of COVID-19 Infection in South Korea. Disaster Med Public Health Prep 2020; 1-8.^,6464 Clements JM. Knowledge and Behaviors Toward COVID-19 Among US Residents During the Early Days of the Pandemic: Cross-Sectional Online Questionnaire. JMIR Public Health Surveill 2020; 6(2):e19161.^,6868 Huang Y, Wu Q, Wang P, Xu Y, Wang L, Zhao Y, Yao D, Xu Y, Lv Q, Xu S. Measures Undertaken in China to Avoid COVID-19 Infection: Internet-Based, Cross-Sectional Survey Study. J Med Internet Res 2020; 22(5):e18718.^,7373 Feng Y, Marchal T, Sperry T, Yi H. Influence of wind and relative humidity on the social distancing effectiveness to prevent COVID-19 airborne transmission: A numerical study. J Aerosol Sci 2020; 105585.^,7575 Gao Q, Hu Y, Dai Z, Xiao F, Wang J, Wu J. The epidemiological characteristics of 2019 novel coronavirus diseases (COVID-19) in Jingmen, Hubei, China. Medicine 2020; 99(23):e20605.^,7878 Goscé L, Phillips PA, Spinola P, Gupta DRK, Abubakar PI. Modelling SARS-COV2 Spread in London: Approaches to Lift the Lockdown. J Infect 2020; 81(2):260-265.^,8080 Laestadius L, Wang Y, Ben Taleb Z, Kalan ME, Cho Y, Manganello J. Online National Health Agency Mask Guidance for the Public in Light of COVID-19: Content Analysis. JMIR Public Health Surveill 2020; 6(2):e19501^,8282 Chan EYY, Huang Z, Lo ESK, Hung KKC, Wong ELY, Wong SYS. Sociodemographic Predictors of Health Risk Perception, Attitude and Behavior Practices Associated with Health-Emergency Disaster Risk Management for Biological Hazards: The Case of COVID-19 Pandemic in Hong Kong, SAR China. Int J Environ Res Public Health 2020; 17(11):3869.^,8484 Liu X, Luo W-T, Li Y, Li C-N, Hong Z-S, Chen H-L, Xiao F, Xia J-Y. Psychological status and behavior changes of the public during the COVID-19 epidemic in China. Infect Dis Poverty 2020; 9(1):58.^,8585 Lee H, Lee H, Song K-H, Kim ES, Park JS, Jung J, Ahn S, Jeong EK, Park H, Kim HB. Impact of Public Health Interventions on Seasonal Influenza Activity During the SARS-CoV-2 Outbreak in Korea. Clin Infect Dis 2020; ciaa672.^,8787 Liu PL. COVID-19 Information Seeking on Digital Media and Preventive Behaviors: The Mediation Role of Worry. Cyberpsychol Behav Soc Netw 2020; 23(10):677-682.^,8888 Jung F, Krieger V, Hufert FT, Küpper J-H. How we should respond to the Coronavirus SARS-CoV-2 outbreak: A German perspective. Clin Hemorheol Microcirc 2020; 74(4):363-372.^,9292 Wong LP, Alias H, Danaee M, Ziaee M, Abedi F, Ziaee A, Mohajer S, HajiAliBeigloo R, Nia MN, Jamei F, Mazlom SR. Uncovering psychobehavioral implications of SARS-CoV-2 infection in Iran. Transbound Emerg Dis 2020; 10.1111/tbed.13662.
https://doi.org/10.1111/tbed.13662... ^,9393 Zhang R, Li Y, Zhang AL, Wang Y, Molina MJ. Identifying airborne transmission as the dominant route for the spread of COVID-19. Proc Natl Acad Sci USA 2020; 117(26):14857-14863.^,9696 Dkhar SA, Quansar R, Saleem SM, Khan SMS. Knowledge, attitude, and practices related to COVID-19 pandemic among social media users in J&K, India. Indian J Public Health 2020; 64(Supl.):S205-S210. and the literature reviews (n=10)¹⁰10 Liang M, Gao L, Cheng C, Zhou Q, Uy JP, Heiner K, Sun C. Efficacy of face mask in preventing respiratory virus transmission: A systematic review and meta-analysis. Travel Med Infect Dis 2020; 36:101751.^,2828 Adhikari SP, Meng S, Wu Y-J, Mao Y-P, Ye R-X, Wang Q-Z, Sun C, Sylvia S, Rozelle S, Raat H, Zhou H. Epidemiology, causes, clinical manifestation and diagnosis, prevention and control of coronavirus disease (COVID-19) during the early outbreak period: a scoping review. Infect Dis Poverty 2020; 9(1):29.^,3939 Gandhi M, Havlir D. The Time for Universal Masking of the Public for Coronavirus Disease 2019 Is Now. Open Forum Infect Dis 2020; 7(4):ofaa131.^,4545 Abd-Elsayed A, Karri J. Utility of Substandard Face Mask Options for Health Care Workers During the COVID-19 Pandemic. Anesth Analg; 131(1):4-6 .^,6060 MacIntyre CR, Chughtai AA. A rapid systematic review of the efficacy of face masks and respirators against coronaviruses and other respiratory transmissible viruses for the community, healthcare workers and sick patients. Int J Nurs Stud 2020; 108:103629.^,6565 Esposito S, Principi N. To mask or not to mask children to overcome COVID-19. Eur J Pediatr 2020; 179(8):1267-1270.^,7676 Clase CM, Fu EL, Joseph M, Beale RCL, Dolovich MB, Jardine M, Mann JFE, Pecoits-Filho R, Winkelmayer WC, Carrero JJ. Cloth Masks May Prevent Transmission of COVID-19: An Evidence-Based, Risk-Based Approach. Ann Intern Med 2020; 173(6):489-491 .^,8686 Chu DK, Akl EA, Duda S, Solo K, Yaacoub S, Schünemann HJ, COVID-19 Systematic Urgent Review Group Effort (SURGE) study authors. Physical distancing, face masks, and eye protection to prevent person-to-person transmission of SARS-CoV-2 and COVID-19: a systematic review and meta-analysis. Lancet 2020; 395(10242):1973-1987^,8989 Li DTS, Samaranayake LP, Leung YY, Neelakantan P. Facial protection in the era of COVID-19: A narrative review. Oral Dis 2020; 10.1111/odi.13460.
https://doi.org/10.1111/odi.13460... ^,9090 Goh Y, Tan BYQ, Bhartendu C, Ong JJY, Sharma VK. The face mask: How a real protection becomes a psychological symbol during Covid-19? Brain Behav Immun 2020; 88:1-5.^,9595 Esposito S, Principi N, Leung CC, Migliori GB. Universal use of face masks for success against COVID-19: evidence and implications for prevention policies. Eur Respir J 2020; 55(6):2001260., among 35 and 15 existing studies for these categories respectively (Chart 1). The first publications about the theme were divided among those discussing the potential implications of widespread use of masks on mask supply and on the recommendation for use of masks as an additional protective measure to prevent pandemic spread. From April onwards, recommendations of widespread use of masks grew from 9.72% (n=7)¹⁸18 Ma QX, Shan H, Zhang HL, Li GM. Potential utilities of mask-wearing and instant hand hygiene for fighting SARS-CoV-2. J Med Virol 2020; 92(9):1567-1571.^,2626 Leung CC, Lam TH, Cheng KK. Let us not forget the mask in our attempts to stall the spread of COVID-19. Int J Tuberc Lung Dis 2020; 24(4):364-366.

27 Zhong B-L, Luo W, Li H-M, Zhang Q-Q, Liu X-G, Li W-T, Li Y. Knowledge, attitudes, and practices towards COVID-19 among Chinese residents during the rapid rise period of the COVID-19 outbreak: a quick online cross-sectional survey. Int J Biol Sci 2020; 16(10):1745-1752.

28 Adhikari SP, Meng S, Wu Y-J, Mao Y-P, Ye R-X, Wang Q-Z, Sun C, Sylvia S, Rozelle S, Raat H, Zhou H. Epidemiology, causes, clinical manifestation and diagnosis, prevention and control of coronavirus disease (COVID-19) during the early outbreak period: a scoping review. Infect Dis Poverty 2020; 9(1):29.

29 Leung CC, Lam TH, Cheng KK. Mass masking in the COVID-19 epidemic: people need guidance. Lancet 2020; 395(10228):945.

30 Zhai Z. Facial mask: A necessity to beat COVID-19. Build Environ 2020; 175:106827.^-3131 Liu X, Zhang S. COVID-19: Face masks and human-to-human transmission. Influenza Other Respi Viruses 2020; 14(4):472-473 . to 90.28% (n=65)¹⁰10 Liang M, Gao L, Cheng C, Zhou Q, Uy JP, Heiner K, Sun C. Efficacy of face mask in preventing respiratory virus transmission: A systematic review and meta-analysis. Travel Med Infect Dis 2020; 36:101751.^,3333 Worby CJ, Chang H-H. Face mask use in the general population and optimal resource allocation during the COVID-19 pandemic. Nat Commun 2020; 11(1):4049.

34 Zhou Z-G, Yue D-S, Mu C-L, Zhang L. Mask is the possible key for self-isolation in COVID-19 pandemic. J Med Virol 2020; 10.1002/jmv.25846.
https://doi.org/10.1002/jmv.25846...

35 Javid B, Weekes MP, Matheson NJ. Covid-19: should the public wear face masks? BMJ 2020; 369:m1442.

36 Greenhalgh T, Schmid MB, Czypionka T, Bassler D, Gruer L. Face masks for the public during the covid-19 crisis. BMJ 2020; 369:m1435.

37 Wang M-W, Cheng Y-R, Ye L, Zhou M-Y, Chen J, Feng Z-H. The COVID-19 outbreak: The issue of face masks. Infect Control Hosp Epidemiol 2020; 41(8):974-975.

38 Han G, Zhou Y-H. Possibly critical role of wearing masks in general population in controlling COVID-19. J Med Virol 2020; 10.1002/jmv.25886.
https://doi.org/10.1002/jmv.25886...

39 Gandhi M, Havlir D. The Time for Universal Masking of the Public for Coronavirus Disease 2019 Is Now. Open Forum Infect Dis 2020; 7(4):ofaa131.

40 Cheng KK, Lam TH, Leung CC. Wearing face masks in the community during the COVID-19 pandemic: altruism and solidarity. Lancet 2020; S0140-6736(20)30918-1 .

41 Pleil JD, Beauchamp JD, Risby TH, Dweik RA. The scientific rationale for the use of simple masks or improvised facial coverings to trap exhaled aerosols and possibly reduce the breathborne spread of COVID-19. J Breath Res 2020; 14(3):030201.

42 Cowling BJ, Ali ST, Ng TWY, Tsang TK, Li JCM, Fong MW, Liao Q, Kwan MY, Lee SL, Chiu SS, Wu JT, Wu P, Leung GM. Impact assessment of non-pharmaceutical interventions against coronavirus disease 2019 and influenza in Hong Kong: an observational study. Lancet Public Health 2020; ;5(5):e279-e288 .

43 Desai AN, Aronoff DM. Masks and Coronavirus Disease 2019 (COVID-19). JAMA 2020; 323(20):2103.

44 MacIntyre CR, Hasanain SJ. Community Universal Face Mask Use during the COVID 19 pandemic-from households to travelers and public spaces. J Travel Med 2020; 27(3):taaa056.

45 Abd-Elsayed A, Karri J. Utility of Substandard Face Mask Options for Health Care Workers During the COVID-19 Pandemic. Anesth Analg; 131(1):4-6 .

46 Eikenberry SE, Mancuso M, Iboi E, Phan T, Eikenberry K, Kuang Y, Kostelich E, Gumel AB. To mask or not to mask: Modeling the potential for face mask use by the general public to curtail the COVID-19 pandemic. Infect Dis Model 2020; 5:293-308.

47 Thomson GA. COVID-19: Leaving lockdown-Of Schrodinger, cats, testing and masks. Int J Clin Pract 2020; 74(8):e13519.

48 Garcia LP. Use of facemasks to limit COVID-19 transmission. Epidemiol Serv Saude 2020; 29(2):e2020023.

49 Chen X, Ran L, Liu Q, Hu Q, Du X, Tan X. Hand Hygiene, Mask-Wearing Behaviors and Its Associated Factors during the COVID-19 Epidemic: A Cross-Sectional Study among Primary School Students in Wuhan, China. Int J Environ Res Public Health 2020; 17(8):2893.

50 Lee M, You M. Psychological and Behavioral Responses in South Korea During the Early Stages of Coronavirus Disease 2019 (COVID-19). Int J Environ Res Public Health 2020; 17(9):2977.

51 Cho-Han Chiang, Cho-Hung Chiang, Cho-Hsien Chiang, Yee-Chun Chen. The Practice of Wearing Surgical Masks during the COVID-19 Pandemic. Emerg Infect Dis 2020; 26(8):1962.

52 Setti L, Passarini F, De Gennaro G, Barbieri P, Perrone MG, Borelli M, Palmisani J, Di Gilio A, Piscitelli P, Miani A. Airborne Transmission Route of COVID-19: Why 2 Meters/6 Feet of Inter-Personal Distance Could Not Be Enough. Int J Environ Res Public Health 2020; 17(8):2932.

53 Cheng VCC, Wong S-C, Chuang VWM, So SY-C, Chen JH-K, Sridhar S, To KK-W, Chan JF-W, Hung IF-N, Ho P-L, Yuen K-Y. The role of community-wide wearing of face mask for control of coronavirus disease 2019 (COVID-19) epidemic due to SARS-CoV-2. J Infect 2020; 81(1):107-114.

54 Konda A, Prakash A, Moss GA, Schmoldt M, Grant GD, Guha S. Aerosol Filtration Efficiency of Common Fabrics Used in Respiratory Cloth Masks. ACS Nano 2020; 14(5):6339-6347.

55 Victor CWT, Shing YT, Wai KP, Helen KWL, Shara WYL. A reality check on the use of face masks during the COVID-19 outbreak in Hong Kong. EClinicalMedicine 2020; 22:100356.

56 Wu E, Qi D. Masks and thermometers: Paramount measures to stop the rapid spread of SARS-CoV-2 in the United States. Genes Dis 2020; 10.1016/j.gendis.2020.04.011.
https://doi.org/10.1016/j.gendis.2020.04...

57 Wilson AM, Abney SE, King M-F, Weir MH, López-García M, Sexton JD, Dancer SJ, Proctor J, Noakes CJ, Reynolds KA. COVID-19 and non-traditional mask use: How do various materials compare in reducing the infection risk for mask wearers? J Hosp Infect 2020; 105(4):640-642.

58 Sunjaya AP, Jenkins C. Rationale for universal face masks in public against COVID-19. Respirology 2020; 5(7):678-679.

59 Ngonghala CN, Iboi E, Eikenberry S, Scotch M, MacIntyre CR, Bonds MH, Gumel AB. Mathematical assessment of the impact of non-pharmaceutical interventions on curtailing the 2019 novel Coronavirus. Math Biosci 2020; 325:108364.

60 MacIntyre CR, Chughtai AA. A rapid systematic review of the efficacy of face masks and respirators against coronaviruses and other respiratory transmissible viruses for the community, healthcare workers and sick patients. Int J Nurs Stud 2020; 108:103629.

61 Hoertel N, Blachier M, Blanco C, Olfson M, Massetti M, Rico MS, Limosin F, Leleu H. Lockdown exit strategies and risk of a second epidemic peak: a stochastic agent-based model of SARS-CoV-2 epidemic in France. medRxiv 2020; 10.1101/2020.04.30.20086264.
https://doi.org/10.1101/2020.04.30.20086...

62 Szczesniak D, Ciulkowicz M, Maciaszek J, Misiak B, Luc D, Wieczorek T, Witecka K-F, Rymaszewska J. Psychopathological responses and face mask restrictions during the COVID-19 outbreak: Results from a nationwide survey. Brain Behav Immun 2020; 87:161-162.

63 Kang Y-J. Lessons Learned From Cases of COVID-19 Infection in South Korea. Disaster Med Public Health Prep 2020; 1-8.

64 Clements JM. Knowledge and Behaviors Toward COVID-19 Among US Residents During the Early Days of the Pandemic: Cross-Sectional Online Questionnaire. JMIR Public Health Surveill 2020; 6(2):e19161.

65 Esposito S, Principi N. To mask or not to mask children to overcome COVID-19. Eur J Pediatr 2020; 179(8):1267-1270.

66 Parry J. Covid-19: Hong Kong government supplies reusable face masks to all residents. BMJ 2020; 369:m1880.

67 Soto DM, Cardona Maya WD, Agudelo EL, Bueno-Sánchez JC. The feasibility of generalized face mask usage during the COVID-19 pandemic: a perspective from Latin America. Infect Control Hosp Epidemiol 2020; 1-2.

68 Huang Y, Wu Q, Wang P, Xu Y, Wang L, Zhao Y, Yao D, Xu Y, Lv Q, Xu S. Measures Undertaken in China to Avoid COVID-19 Infection: Internet-Based, Cross-Sectional Survey Study. J Med Internet Res 2020; 22(5):e18718.

69 Sra HK, Sandhu A, Singh M. Use of Face Masks in COVID-19. Indian J Pediatr 2020; 87:553.

70 Kashyap A, Singh K, Sabat D, Maini L. Fast and economic cardboard cutout use to increase compliance of face mask wear during COVID-19 pandemic. J Clin Orthop Trauma 2020; 11(Supl. 3):S298-S300.

71 Matusiak L, Szepietowska M, Krajewski P, Bialynicki-Birula R, Szepietowski JC. Inconveniences due to the use of face masks during the COVID-19 pandemic: A survey study of 876 young people. Dermatol Ther 2020; 33(4):e13567.

72 Ogoina D. COVID-19: The Need for Rational Use of Face Masks in Nigeria. Am J Trop Med Hyg 2020; 103(1):33-34.

73 Feng Y, Marchal T, Sperry T, Yi H. Influence of wind and relative humidity on the social distancing effectiveness to prevent COVID-19 airborne transmission: A numerical study. J Aerosol Sci 2020; 105585.

74 Noh JY, Seong H, Yoon JG, Song JY, Cheong HJ, Kim WJ. Social Distancing against COVID-19: Implication for the Control of Influenza. J Korean Med Sci 2020; 35(19):e182.

75 Gao Q, Hu Y, Dai Z, Xiao F, Wang J, Wu J. The epidemiological characteristics of 2019 novel coronavirus diseases (COVID-19) in Jingmen, Hubei, China. Medicine 2020; 99(23):e20605.

76 Clase CM, Fu EL, Joseph M, Beale RCL, Dolovich MB, Jardine M, Mann JFE, Pecoits-Filho R, Winkelmayer WC, Carrero JJ. Cloth Masks May Prevent Transmission of COVID-19: An Evidence-Based, Risk-Based Approach. Ann Intern Med 2020; 173(6):489-491 .

77 Chiang C-H, Chiang C-H, Chiang C-H. Letter to editor - Can universal masking help with our recovery from the COVID-19 pandemic? Int J Surg 2020; 79:125-126.

78 Goscé L, Phillips PA, Spinola P, Gupta DRK, Abubakar PI. Modelling SARS-COV2 Spread in London: Approaches to Lift the Lockdown. J Infect 2020; 81(2):260-265.

79 Middleton JD, Lopes H. Face masks in the covid-19 crisis: caveats, limits, and priorities. BMJ 2020; 369:m2030.

80 Laestadius L, Wang Y, Ben Taleb Z, Kalan ME, Cho Y, Manganello J. Online National Health Agency Mask Guidance for the Public in Light of COVID-19: Content Analysis. JMIR Public Health Surveill 2020; 6(2):e19501

81 Majeed A, Seo Y, Heo K, Lee D. Can the UK emulate the South Korean approach to covid-19? BMJ 2020; 369:m2084.

82 Chan EYY, Huang Z, Lo ESK, Hung KKC, Wong ELY, Wong SYS. Sociodemographic Predictors of Health Risk Perception, Attitude and Behavior Practices Associated with Health-Emergency Disaster Risk Management for Biological Hazards: The Case of COVID-19 Pandemic in Hong Kong, SAR China. Int J Environ Res Public Health 2020; 17(11):3869.

83 Han C, Shi J, Chen Y, Zhang Z. Increased flare of acne caused by long-time mask wearing during COVID-19 pandemic among general population. Dermatol Ther 2020; 33(4):e13704.

84 Liu X, Luo W-T, Li Y, Li C-N, Hong Z-S, Chen H-L, Xiao F, Xia J-Y. Psychological status and behavior changes of the public during the COVID-19 epidemic in China. Infect Dis Poverty 2020; 9(1):58.

85 Lee H, Lee H, Song K-H, Kim ES, Park JS, Jung J, Ahn S, Jeong EK, Park H, Kim HB. Impact of Public Health Interventions on Seasonal Influenza Activity During the SARS-CoV-2 Outbreak in Korea. Clin Infect Dis 2020; ciaa672.

86 Chu DK, Akl EA, Duda S, Solo K, Yaacoub S, Schünemann HJ, COVID-19 Systematic Urgent Review Group Effort (SURGE) study authors. Physical distancing, face masks, and eye protection to prevent person-to-person transmission of SARS-CoV-2 and COVID-19: a systematic review and meta-analysis. Lancet 2020; 395(10242):1973-1987

87 Liu PL. COVID-19 Information Seeking on Digital Media and Preventive Behaviors: The Mediation Role of Worry. Cyberpsychol Behav Soc Netw 2020; 23(10):677-682.

88 Jung F, Krieger V, Hufert FT, Küpper J-H. How we should respond to the Coronavirus SARS-CoV-2 outbreak: A German perspective. Clin Hemorheol Microcirc 2020; 74(4):363-372.

89 Li DTS, Samaranayake LP, Leung YY, Neelakantan P. Facial protection in the era of COVID-19: A narrative review. Oral Dis 2020; 10.1111/odi.13460.
https://doi.org/10.1111/odi.13460...

90 Goh Y, Tan BYQ, Bhartendu C, Ong JJY, Sharma VK. The face mask: How a real protection becomes a psychological symbol during Covid-19? Brain Behav Immun 2020; 88:1-5.

91 Greenhalgh T. Laying straw men to rest: author's reply to 'Urgency and uncertainty: covid-19, face masks, and evidence informed policy'. BMJ 2020; 369:m2240

92 Wong LP, Alias H, Danaee M, Ziaee M, Abedi F, Ziaee A, Mohajer S, HajiAliBeigloo R, Nia MN, Jamei F, Mazlom SR. Uncovering psychobehavioral implications of SARS-CoV-2 infection in Iran. Transbound Emerg Dis 2020; 10.1111/tbed.13662.
https://doi.org/10.1111/tbed.13662...

93 Zhang R, Li Y, Zhang AL, Wang Y, Molina MJ. Identifying airborne transmission as the dominant route for the spread of COVID-19. Proc Natl Acad Sci USA 2020; 117(26):14857-14863.

94 Ho K-F, Lin L-Y, Weng S-P, Chuang K-J. Medical mask versus cotton mask for preventing respiratory droplet transmission in micro environments. Sci Total Environ 2020; 735:139510.

95 Esposito S, Principi N, Leung CC, Migliori GB. Universal use of face masks for success against COVID-19: evidence and implications for prevention policies. Eur Respir J 2020; 55(6):2001260.^-9696 Dkhar SA, Quansar R, Saleem SM, Khan SMS. Knowledge, attitude, and practices related to COVID-19 pandemic among social media users in J&K, India. Indian J Public Health 2020; 64(Supl.):S205-S210.. This difference can also be observed among countries (Figure 4), which began to recommend the use of cloth masks when outside the house from April onwards (the different dates in which countries adopted the measure can be assessed on Table 1).

The evolution of recommendations regarding the use of cloth masks to prevent the spread of COVID-19 throughout the course of the pandemic

As the COVID-19 pandemic advanced, discussions began to be held on the use of masks in public spaces as a public health intervention, with some favorable opinions^{10,18,20,26-31,34,35,37,39-82,84-96,102,103,116-120} and some opposing views⁹⁷97 Mahase E. Covid-19: What is the evidence for cloth masks? BMJ 2020; 369:m1422.

98 Szarpak L, Smereka J, Filipiak KJ, Ladny JR, Jaguszewski M. Cloth masks versus medical masks for COVID-19 protection. Cardiol J 2020; 27(2):218-219.

99 Lazcano-Ponce E, Alpuche-Aranda C. Public health literacy in the face of the Covid-19 pandemic emergency. Salud Publica Mex 2020; 62(3):331-340.^-100100 Martin GP, Hanna E, Dingwall R. Urgency and uncertainty: covid-19, face masks, and evidence informed policy. BMJ 2020; 369:m2017.. Opinions against the widespread use of masks⁹⁷97 Mahase E. Covid-19: What is the evidence for cloth masks? BMJ 2020; 369:m1422.

98 Szarpak L, Smereka J, Filipiak KJ, Ladny JR, Jaguszewski M. Cloth masks versus medical masks for COVID-19 protection. Cardiol J 2020; 27(2):218-219.

99 Lazcano-Ponce E, Alpuche-Aranda C. Public health literacy in the face of the Covid-19 pandemic emergency. Salud Publica Mex 2020; 62(3):331-340.^-100100 Martin GP, Hanna E, Dingwall R. Urgency and uncertainty: covid-19, face masks, and evidence informed policy. BMJ 2020; 369:m2017. in public spaces were found mainly up to the first week of March and were based on suppositions that: i) this recommendation could result in the population relaxing social distancing measures⁹9 World Health Organization (WHO). Responding to community spread of COVID-19: interim guidance [Internet]. Genebra: WHO; 2020 [acessado 2020 Maio 6]. Disponível em: https://apps.who.int/iris/handle/10665/331421^,121121 World Health Organization (WHO). Rational use of personal protective equipment for coronavirus disease (COVID-19): interim guidance, 27 February 2020. Genebra: WHO; 2020.; ii) inappropriate handling and use of masks could increase the risk of transmission of the novel coronavirus¹²²122 Bamber JH, Christmas T. Covid-19: Each discarded face mask is a potential biohazard. BMJ 2020; 369:m2012.; iii) the increased demand for masks could aggravate the shortage of surgical masks for healthcare professionals¹⁸18 Ma QX, Shan H, Zhang HL, Li GM. Potential utilities of mask-wearing and instant hand hygiene for fighting SARS-CoV-2. J Med Virol 2020; 92(9):1567-1571.^,2121 Feng S, Shen C, Xia N, Song W, Fan M, Cowling BJ. Rational use of face masks in the COVID-19 pandemic. Lancet Respir Med 2020; 8(5):434-436.^,6969 Sra HK, Sandhu A, Singh M. Use of Face Masks in COVID-19. Indian J Pediatr 2020; 87:553.^,121121 World Health Organization (WHO). Rational use of personal protective equipment for coronavirus disease (COVID-19): interim guidance, 27 February 2020. Genebra: WHO; 2020.^,123123 Todd B. Where Are the Masks? Am J Nurs 2020; 120(6):18-19.^,124124 Lepelletier D, Grandbastien B, Romano-Bertrand S, Aho S, Chidiac C, Géhanno J-F, Chauvin F, French Society for Hospital Hygiene and the High Council for Public Health. What face mask for what use in the context of COVID-19 pandemic? The French guidelines. J Hosp Infect 2020; 105(3):414-418.; and iv) this recommendation could result in unscrupulous price increases. We highlight, once more, that the published materials that were contrary to the use of cloth masks by the general public were exclusively opinion pieces, commentaries and editorials, which did not present scientific evidence that cloth mask use was ineffective in preventing the dissemination of the disease⁹⁷97 Mahase E. Covid-19: What is the evidence for cloth masks? BMJ 2020; 369:m1422.

98 Szarpak L, Smereka J, Filipiak KJ, Ladny JR, Jaguszewski M. Cloth masks versus medical masks for COVID-19 protection. Cardiol J 2020; 27(2):218-219.

99 Lazcano-Ponce E, Alpuche-Aranda C. Public health literacy in the face of the Covid-19 pandemic emergency. Salud Publica Mex 2020; 62(3):331-340.^-100100 Martin GP, Hanna E, Dingwall R. Urgency and uncertainty: covid-19, face masks, and evidence informed policy. BMJ 2020; 369:m2017..

Evidence regarding the use of masks in public spaces to prevent the spread of respiratory infectious diseases

Studies conducted prior to the current pandemic had already confirmed the effectiveness of the widespread use of facemasks, including cloth masks, outside the home as a strategy for controlling the spread of infectious respiratory diseases¹⁰10 Liang M, Gao L, Cheng C, Zhou Q, Uy JP, Heiner K, Sun C. Efficacy of face mask in preventing respiratory virus transmission: A systematic review and meta-analysis. Travel Med Infect Dis 2020; 36:101751.^,1818 Ma QX, Shan H, Zhang HL, Li GM. Potential utilities of mask-wearing and instant hand hygiene for fighting SARS-CoV-2. J Med Virol 2020; 92(9):1567-1571.^,4444 MacIntyre CR, Hasanain SJ. Community Universal Face Mask Use during the COVID 19 pandemic-from households to travelers and public spaces. J Travel Med 2020; 27(3):taaa056.^,5656 Wu E, Qi D. Masks and thermometers: Paramount measures to stop the rapid spread of SARS-CoV-2 in the United States. Genes Dis 2020; 10.1016/j.gendis.2020.04.011.
https://doi.org/10.1016/j.gendis.2020.04... ^,125125 Brienen NCJ, Timen A, Wallinga J, van Steenbergen JE, Teunis PFM. The effect of mask use on the spread of influenza during a pandemic. Risk Anal 2010; 30(8):1210-1218.^,126126 Davies A, Thompson K-A, Giri K, Kafatos G, Walker J, Bennett A. Testing the efficacy of homemade masks: would they protect in an influenza pandemic? Disaster Med Public Health Prep 2013; 7(4):413-418., including SARS¹²⁷127 Leung GM, Ho L-M, Chan SKK, Ho S-Y, Bacon-Shone J, Choy RYL, Hedley AJ, Lam T-H, Fielding R. Longitudinal assessment of community psychobehavioral responses during and after the 2003 outbreak of severe acute respiratory syndrome in Hong Kong. Clin Infect Dis 2005; 40(12):1713-1720.. According to a study conducted in the United Kingdom¹²⁸128 Howard J, Huang A, Li Z, Tufekci Z, Zdimal V, van der Westhuizen H, von Delft A, Price A, Fridman L, Tang L, Tan V, Watson GL, Bax CE, Shaikh R, Questier F, Hernandez D, Chu LF, Ramirez CM, Rimoin AW. Face masks against COVID-19: an evidence review. Preprints 2020; 10.20944/preprints202004.0203.v1.
https://doi.org/10.20944/preprints202004... , the effectiveness of the use of masks in combatting respiratory diseases depends on three main factors: i) the capacity of the mask to block the virus (its effectiveness); ii) the proportion of individuals wearing masks in public spaces (compliance with use); and iii) the rate of transmission of the disease.

Studies also suggest that, although their effectiveness is less than that found with surgical masks, cloth masks, if used properly, act as a mechanical barrier against transmission of the virus, preventing or reducing contact between individuals and contaminated droplets¹⁸18 Ma QX, Shan H, Zhang HL, Li GM. Potential utilities of mask-wearing and instant hand hygiene for fighting SARS-CoV-2. J Med Virol 2020; 92(9):1567-1571.^,5757 Wilson AM, Abney SE, King M-F, Weir MH, López-García M, Sexton JD, Dancer SJ, Proctor J, Noakes CJ, Reynolds KA. COVID-19 and non-traditional mask use: How do various materials compare in reducing the infection risk for mask wearers? J Hosp Infect 2020; 105(4):640-642.^,104104 Amendola L, Saurini MT, Di Girolamo F, Arduini F. A rapid screening method for testing the efficiency of masks in breaking down aerosols. Microchem J 2020; 157:104928.^,105105 Kim MN. What Type of Face Mask Is Appropriate for Everyone-Mask-Wearing Policy amidst COVID-19 Pandemic? J Korean Med Sci 2020; 35(20):e186.^,125125 Brienen NCJ, Timen A, Wallinga J, van Steenbergen JE, Teunis PFM. The effect of mask use on the spread of influenza during a pandemic. Risk Anal 2010; 30(8):1210-1218.^,126126 Davies A, Thompson K-A, Giri K, Kafatos G, Walker J, Bennett A. Testing the efficacy of homemade masks: would they protect in an influenza pandemic? Disaster Med Public Health Prep 2013; 7(4):413-418.^,129129 Milton DK, Fabian MP, Cowling BJ, Grantham ML, McDevitt JJ. Influenza virus aerosols in human exhaled breath: particle size, culturability, and effect of surgical masks. PLoS Pathog 2013; 9(3):e1003205.^,130130 Lustig SR, Biswakarma JJH, Rana D, Tilford SH, Hu W, Su M, Rosenblatt MS. Effectiveness of Common Fabrics to Block Aqueous Aerosols of Virus-like Nanoparticles. ACS Nano 2020; 14(6):7651-7658.. This reduction occurs because, if a contaminated droplet falls on the woven fabric of a mask instead of on an individual’s mouth or nose, it tends to be retained in the fabric weave, hence reducing the number of contaminated droplets that reach the respiratory tract. By avoiding contamination of the user, cloth masks help defer the spread of the epidemic³⁸38 Han G, Zhou Y-H. Possibly critical role of wearing masks in general population in controlling COVID-19. J Med Virol 2020; 10.1002/jmv.25886.
https://doi.org/10.1002/jmv.25886... and contribute towards establishing a longer and flatter epidemic curve⁹⁷97 Mahase E. Covid-19: What is the evidence for cloth masks? BMJ 2020; 369:m1422.. Nevertheless, if the masks are positioned on users’ faces inadequately, with open lateral spaces, for example, they can have their protective effect reduced by up to 60%⁵⁴54 Konda A, Prakash A, Moss GA, Schmoldt M, Grant GD, Guha S. Aerosol Filtration Efficiency of Common Fabrics Used in Respiratory Cloth Masks. ACS Nano 2020; 14(5):6339-6347..

Researchers at Duke University in the United States analyzed 14 types of mask to evaluate their effectiveness in protecting against respiratory droplets from speech. The results showed that, indeed, the N95 professional masks are the most effective (droplet transmission was reduced to less than 0.1%), followed by 3-layer surgical masks or cotton-polypropylene masks (droplet transmission reduced by 90% or more compared to no facial covering). Handmade cotton facemasks are the next most effective, offering good protection and eliminating 70-90% of droplets from speech, with a performance that is equivalent to that of N95 masks fitted with respiratory valves¹³¹131 Fischer EP, Fischer MC, Grass D, Henrion I, Warren WS, Westman E. Low-cost measurement of face mask efficacy for filtering expelled droplets during speech. Sci Adv 2020; 6(36):eabd3083..

Also, with respect to the filtration efficiency of cloth masks, a study conducted in Taipei found no statistically significant differences in the concentration of aerosol particles in the 20-1,000 nm range in enclosed spaces (car and bedroom) following the presence of persons with influenza using 3-layer cloth masks versus those same individuals using surgical masks⁹⁴94 Ho K-F, Lin L-Y, Weng S-P, Chuang K-J. Medical mask versus cotton mask for preventing respiratory droplet transmission in micro environments. Sci Total Environ 2020; 735:139510., suggesting that the filtration efficiency of both models was similar. In the United States, in view of the shortage of professional masks during the COVID-19 pandemic, the Centers for Disease Control and Prevention (CDC) even issued a recommendation for healthcare professionals not working directly with infected patients to use cloth masks⁴⁵45 Abd-Elsayed A, Karri J. Utility of Substandard Face Mask Options for Health Care Workers During the COVID-19 Pandemic. Anesth Analg; 131(1):4-6 ..

Evidence regarding the use of cloth masks in public spaces to prevent COVID-19

In relation to the proportion of individuals who wear masks, there are considerable differences in the regulations adopted in different countries and regions and also in the compliance rates of the population with these measures, even when the use of masks is recommended. The compliance of individuals with the prevention measure depends, among other factors, on the consistency of the information provided by the public authorities, the trust of the population in the public and health authorities and on the population’s knowledge regarding the disease¹³²132 Goodman JL, Borio L. Finding Effective Treatments for COVID-19: Scientific Integrity and Public Confidence in a Time of Crisis. JAMA 2020; 323(19):1899-1900.. Nevertheless, at the end of March, around three months after the beginning of the pandemic, Laestadius et al.⁸⁰80 Laestadius L, Wang Y, Ben Taleb Z, Kalan ME, Cho Y, Manganello J. Online National Health Agency Mask Guidance for the Public in Light of COVID-19: Content Analysis. JMIR Public Health Surveill 2020; 6(2):e19501 evaluated the guidelines and information on the use of masks on the official sites of health agencies and ministries of 25 countries and reported a lack of standardization and alignment of the information provided to the public.

The first country to make the use of masks in public spaces obligatory was Mongolia on March 14, followed by Vietnam, Venezuela and the Czech Republic¹³³133 Masks4All. Quais países exigem máscaras em público ou recomendam máscaras? [Internet]. [acessado 2020 Jul 11]. Disponível em: https://masks4all.co/pt/what-countries-require-masks-in-public/
https://masks4all.co/pt/what-countries-r... (Table 1). Up to July 13, 2020, six months after the beginning of the pandemic, 129 countries had begun to recommend the widespread use of masks in public spaces, either in general or in a more restricted manner. In another 17 countries, the need to wear a mask was obligatory in only parts of the country (municipalities/states)¹³³133 Masks4All. Quais países exigem máscaras em público ou recomendam máscaras? [Internet]. [acessado 2020 Jul 11]. Disponível em: https://masks4all.co/pt/what-countries-require-masks-in-public/
https://masks4all.co/pt/what-countries-r... . Hence, of the 193 sovereign states, up to July 13, 146 had adopted the use of masks as a means of preventing the dissemination of COVID-19, highlighting the relevance of this measure from a public health viewpoint (Figure 4). According to Li et al.⁸⁹89 Li DTS, Samaranayake LP, Leung YY, Neelakantan P. Facial protection in the era of COVID-19: A narrative review. Oral Dis 2020; 10.1111/odi.13460.
https://doi.org/10.1111/odi.13460... , the efficacy of mandatory use of cloth masks is one of the greatest lessons from this pandemic. Today, masks are considered to be able to reduce the severity of COVID-19, and to create the possibility that new infections are asymptomatic¹³⁴134 Gandhi M, Rutherford GW. Facial Masking for Covid-19 - Potential for 'Variolation' as We Await a Vaccine. N Engl J Med 2020; 383(18):e101..

Some countries recommended the use of masks at the beginning of the pandemic even in the absence of consolidated scientific evidence on the effectiveness of the measure in reducing the rate of spread of the virus⁸¹81 Majeed A, Seo Y, Heo K, Lee D. Can the UK emulate the South Korean approach to covid-19? BMJ 2020; 369:m2084., possibly based on the precautionary principle, which is defined as a strategy for approaching issues of potential harm when extensive scientific knowledge on the matter is lacking. According to Greenhalgh et al.³⁶36 Greenhalgh T, Schmid MB, Czypionka T, Bassler D, Gruer L. Face masks for the public during the covid-19 crisis. BMJ 2020; 369:m1435., this principle must be applied to relevant questions involved in protecting public health, particularly when cost-benefit analyses suggest few potential adverse effects and the possibility of achieving significant benefits¹³⁵135 Brooks JT, Butler JC, Redfield RR. Universal Masking to Prevent SARS-CoV-2 Transmission-The Time Is Now. JAMA 2020; 10.1001/jama.2020.13107.
https://doi.org/10.1001/jama.2020.13107... .

The beneficial effects of the early adoption of cloth masks in some countries were evident in studies that compared the spread of COVID-19 in different regions and in those that screened for cases of SARS-CoV-2 infection. One transnational study, for example, compared the spread of the pandemic in Austria and the Czech Republic, with results suggesting the effectiveness of the use of masks in combatting COVID-19¹²⁸128 Howard J, Huang A, Li Z, Tufekci Z, Zdimal V, van der Westhuizen H, von Delft A, Price A, Fridman L, Tang L, Tan V, Watson GL, Bax CE, Shaikh R, Questier F, Hernandez D, Chu LF, Ramirez CM, Rimoin AW. Face masks against COVID-19: an evidence review. Preprints 2020; 10.20944/preprints202004.0203.v1.
https://doi.org/10.20944/preprints202004... . Both countries established social distancing requirements on the same date; however, only the Czech Republic simultaneously incorporated the obligatory use of masks. From then on, the number of coronavirus infections in Austria was seen to rise, while in the Czech Republic the epidemic curve remained long and flat. It was only when Austria also made the use of masks obligatory by governmental decree that the curves returned to similar trajectories¹²⁸128 Howard J, Huang A, Li Z, Tufekci Z, Zdimal V, van der Westhuizen H, von Delft A, Price A, Fridman L, Tang L, Tan V, Watson GL, Bax CE, Shaikh R, Questier F, Hernandez D, Chu LF, Ramirez CM, Rimoin AW. Face masks against COVID-19: an evidence review. Preprints 2020; 10.20944/preprints202004.0203.v1.
https://doi.org/10.20944/preprints202004... .

Likewise, Cheng et al.⁴⁰40 Cheng KK, Lam TH, Leung CC. Wearing face masks in the community during the COVID-19 pandemic: altruism and solidarity. Lancet 2020; S0140-6736(20)30918-1 . compared the course of the incidence of COVID-19 in Hong Kong with the course of the disease in another eight countries, and attributed the low contamination rate in Hong Kong to the universal and voluntary adoption of the use of masks by the majority of the population at the beginning of the pandemic (96.6% during the study). That same study traced some routes of transmission among the first 961 reported cases of the infection in Hong Kong, with findings showing eleven clusters of 113 patients in leisure spaces where masks were not used, including restaurants, karaoke lounges and fitness clubs, and revealing that only three clusters occurred in the workplace environment where masks were required⁵³53 Cheng VCC, Wong S-C, Chuang VWM, So SY-C, Chen JH-K, Sridhar S, To KK-W, Chan JF-W, Hung IF-N, Ho P-L, Yuen K-Y. The role of community-wide wearing of face mask for control of coronavirus disease 2019 (COVID-19) epidemic due to SARS-CoV-2. J Infect 2020; 81(1):107-114.. Other epidemiological studies that followed transmission routes also concluded that transmission rates were lower in situations where masks were used³¹31 Liu X, Zhang S. COVID-19: Face masks and human-to-human transmission. Influenza Other Respi Viruses 2020; 14(4):472-473 .^,7575 Gao Q, Hu Y, Dai Z, Xiao F, Wang J, Wu J. The epidemiological characteristics of 2019 novel coronavirus diseases (COVID-19) in Jingmen, Hubei, China. Medicine 2020; 99(23):e20605..

Based on data from the spread of the pandemic in Italy and New York, both severely affected by COVID-19, Zhang et al.⁹³93 Zhang R, Li Y, Zhang AL, Wang Y, Molina MJ. Identifying airborne transmission as the dominant route for the spread of COVID-19. Proc Natl Acad Sci USA 2020; 117(26):14857-14863. showed that being obliged to cover the nose and mouth avoided more than 76,000 new cases of novel coronavirus infection in Italy and more than 66,000 in New York⁹³93 Zhang R, Li Y, Zhang AL, Wang Y, Molina MJ. Identifying airborne transmission as the dominant route for the spread of COVID-19. Proc Natl Acad Sci USA 2020; 117(26):14857-14863.. The measures that made the use of cloth masks obligatory in public spaces in the states of New York and Washington were adopted after predictive modeling indicated that the widespread adoption of masks, even the less effective ones, could reduce transmission of the novel coronavirus, helping flatten the epidemic curve and the mortality peaks⁴⁶46 Eikenberry SE, Mancuso M, Iboi E, Phan T, Eikenberry K, Kuang Y, Kostelich E, Gumel AB. To mask or not to mask: Modeling the potential for face mask use by the general public to curtail the COVID-19 pandemic. Infect Dis Model 2020; 5:293-308.^,5959 Ngonghala CN, Iboi E, Eikenberry S, Scotch M, MacIntyre CR, Bonds MH, Gumel AB. Mathematical assessment of the impact of non-pharmaceutical interventions on curtailing the 2019 novel Coronavirus. Math Biosci 2020; 325:108364.. According to other studies, the recommendation to maintain a physical distance of two meters from others in public places is only effective if the measure is associated with the use of masks⁵²52 Setti L, Passarini F, De Gennaro G, Barbieri P, Perrone MG, Borelli M, Palmisani J, Di Gilio A, Piscitelli P, Miani A. Airborne Transmission Route of COVID-19: Why 2 Meters/6 Feet of Inter-Personal Distance Could Not Be Enough. Int J Environ Res Public Health 2020; 17(8):2932.^,7373 Feng Y, Marchal T, Sperry T, Yi H. Influence of wind and relative humidity on the social distancing effectiveness to prevent COVID-19 airborne transmission: A numerical study. J Aerosol Sci 2020; 105585. and the COVID-19 pandemic can only be contained if the majority of the population or, preferably, the entire population wears cloth masks in public spaces²¹21 Feng S, Shen C, Xia N, Song W, Fan M, Cowling BJ. Rational use of face masks in the COVID-19 pandemic. Lancet Respir Med 2020; 8(5):434-436.^,118118 Greenhalgh T, Schmid MB, Czypionka T, Bassler D, Gruer L. Face masks for the public during the covid-19 crisis. BMJ 2020; 369:m1435.^,128128 Howard J, Huang A, Li Z, Tufekci Z, Zdimal V, van der Westhuizen H, von Delft A, Price A, Fridman L, Tang L, Tan V, Watson GL, Bax CE, Shaikh R, Questier F, Hernandez D, Chu LF, Ramirez CM, Rimoin AW. Face masks against COVID-19: an evidence review. Preprints 2020; 10.20944/preprints202004.0203.v1.
https://doi.org/10.20944/preprints202004... ^,136136 van der Sande M, Teunis P, Sabel R. Professional and home-made face masks reduce exposure to respiratory infections among the general population. PLoS One 2008; 3(7):e2618..

Brooks et al.¹³⁵135 Brooks JT, Butler JC, Redfield RR. Universal Masking to Prevent SARS-CoV-2 Transmission-The Time Is Now. JAMA 2020; 10.1001/jama.2020.13107.
https://doi.org/10.1001/jama.2020.13107... compared the use of masks with herd immunity obtained through vaccination, since the more people complying with this preventive measure in public areas where social distancing is impossible, the greater the community protection¹³⁵135 Brooks JT, Butler JC, Redfield RR. Universal Masking to Prevent SARS-CoV-2 Transmission-The Time Is Now. JAMA 2020; 10.1001/jama.2020.13107.
https://doi.org/10.1001/jama.2020.13107... . The same authors stated that the collective protection achieved with the use of cloth masks might reduce the number of new infections and avoid the interventions that are more disruptive to society such as closing commercial establishments and imposing lockdown - the public policy that requires citizens to stay at home.

Although several studies have indicated the effectiveness of masks in controlling the pandemic and despite the fact that a growing number of countries now require cloth masks to be used in public spaces, the rate of compliance by populations varies dramatically. Certainly, health authorities’ recommendation to use masks influences the behavior of the population, as shown in a study, still in preprint stage, conducted in the United States. According to that report, there was a 12% increase in the use of masks among Americans in only five days following the announcement by the CDC¹³⁷137 Goldberg MH, Gustafson A, Maibach EW, Ballew MT, Bergquist P, Kotcher JE, Marlon JR, Rosenthal SA, Leiserowitz A. Mask-wearing increases after a government recommendation: A natural experiment in the U.S. during the COVID-19 pandemic. Front Commun 2020; 5(44):1-6.. Nevertheless, of all the studies included in this review, the highest rates of compliance with the use of masks were in the Asian countries that had a previous history of using this resource to control other infectious respiratory diseases and protect against air pollution⁴²42 Cowling BJ, Ali ST, Ng TWY, Tsang TK, Li JCM, Fong MW, Liao Q, Kwan MY, Lee SL, Chiu SS, Wu JT, Wu P, Leung GM. Impact assessment of non-pharmaceutical interventions against coronavirus disease 2019 and influenza in Hong Kong: an observational study. Lancet Public Health 2020; ;5(5):e279-e288 .^,4949 Chen X, Ran L, Liu Q, Hu Q, Du X, Tan X. Hand Hygiene, Mask-Wearing Behaviors and Its Associated Factors during the COVID-19 Epidemic: A Cross-Sectional Study among Primary School Students in Wuhan, China. Int J Environ Res Public Health 2020; 17(8):2893.^,5050 Lee M, You M. Psychological and Behavioral Responses in South Korea During the Early Stages of Coronavirus Disease 2019 (COVID-19). Int J Environ Res Public Health 2020; 17(9):2977.^,9696 Dkhar SA, Quansar R, Saleem SM, Khan SMS. Knowledge, attitude, and practices related to COVID-19 pandemic among social media users in J&K, India. Indian J Public Health 2020; 64(Supl.):S205-S210.^,111111 Azlan AA, Hamzah MR, Sern TJ, Ayub SH, Mohamad E. Public knowledge, attitudes and practices towards COVID-19: A cross-sectional study in Malaysia. PLoS One 2020; 15(5):e0233668..

The populations of South Korea and Singapore, for example, were already wearing masks in public spaces, particularly after the SARS outbreak in 2003, which made it simpler to carry over the measure to the backdrop of the SARS-CoV-2 pandemic. In South Korea, right at the beginning of the pandemic, over 60% of the population were already wearing masks⁵⁰50 Lee M, You M. Psychological and Behavioral Responses in South Korea During the Early Stages of Coronavirus Disease 2019 (COVID-19). Int J Environ Res Public Health 2020; 17(9):2977.. In Hong Kong, the use of masks in public spaces increased from 74.5% to 98.8% among individuals interviewed between January and March 2020⁴²42 Cowling BJ, Ali ST, Ng TWY, Tsang TK, Li JCM, Fong MW, Liao Q, Kwan MY, Lee SL, Chiu SS, Wu JT, Wu P, Leung GM. Impact assessment of non-pharmaceutical interventions against coronavirus disease 2019 and influenza in Hong Kong: an observational study. Lancet Public Health 2020; ;5(5):e279-e288 .. Various studies conducted in Hong Kong reported similar compliance rates of 97% to 99%⁸²82 Chan EYY, Huang Z, Lo ESK, Hung KKC, Wong ELY, Wong SYS. Sociodemographic Predictors of Health Risk Perception, Attitude and Behavior Practices Associated with Health-Emergency Disaster Risk Management for Biological Hazards: The Case of COVID-19 Pandemic in Hong Kong, SAR China. Int J Environ Res Public Health 2020; 17(11):3869., with the widespread use of cloth masks being considered one of the most effective strategies in combatting the pandemic in the region⁴²42 Cowling BJ, Ali ST, Ng TWY, Tsang TK, Li JCM, Fong MW, Liao Q, Kwan MY, Lee SL, Chiu SS, Wu JT, Wu P, Leung GM. Impact assessment of non-pharmaceutical interventions against coronavirus disease 2019 and influenza in Hong Kong: an observational study. Lancet Public Health 2020; ;5(5):e279-e288 .. In China, compliance with the use of masks is over 80%⁶⁸68 Huang Y, Wu Q, Wang P, Xu Y, Wang L, Zhao Y, Yao D, Xu Y, Lv Q, Xu S. Measures Undertaken in China to Avoid COVID-19 Infection: Internet-Based, Cross-Sectional Survey Study. J Med Internet Res 2020; 22(5):e18718.^,8484 Liu X, Luo W-T, Li Y, Li C-N, Hong Z-S, Chen H-L, Xiao F, Xia J-Y. Psychological status and behavior changes of the public during the COVID-19 epidemic in China. Infect Dis Poverty 2020; 9(1):58.^,138138 Chen Y, Jin YL, Zhu LJ, Fang ZM, Wu N, Du MX, Jiang MM, Wang J, Yao YS. The network investigation on knowledge, attitude and practice about COVID-19 of the residents in Anhui Province. Zhonghua Yu Fang Yi Xue Za Zhi 2020; 54(4):367-373.. In comparison, in India and Malaysia studies on the behavior of the population in relation to the pandemic showed lower compliance with masks, which were adopted by 70% and 51% of those interviewed, respectively⁹⁶96 Dkhar SA, Quansar R, Saleem SM, Khan SMS. Knowledge, attitude, and practices related to COVID-19 pandemic among social media users in J&K, India. Indian J Public Health 2020; 64(Supl.):S205-S210.^,111111 Azlan AA, Hamzah MR, Sern TJ, Ayub SH, Mohamad E. Public knowledge, attitudes and practices towards COVID-19: A cross-sectional study in Malaysia. PLoS One 2020; 15(5):e0233668..

The effectiveness of the use of cloth masks in controlling COVID-19 is well supported in the literature when implemented in conjunction with other measures aimed at combatting the pandemic such as effective hand washing and social distancing⁸⁶86 Chu DK, Akl EA, Duda S, Solo K, Yaacoub S, Schünemann HJ, COVID-19 Systematic Urgent Review Group Effort (SURGE) study authors. Physical distancing, face masks, and eye protection to prevent person-to-person transmission of SARS-CoV-2 and COVID-19: a systematic review and meta-analysis. Lancet 2020; 395(10242):1973-1987. The use of cloth masks without the adoption of these other measures cannot, however, be interpreted by the public as a solution to the health crisis, since their efficacy remains controversial when other recommendations are not adhered to⁶⁰60 MacIntyre CR, Chughtai AA. A rapid systematic review of the efficacy of face masks and respirators against coronaviruses and other respiratory transmissible viruses for the community, healthcare workers and sick patients. Int J Nurs Stud 2020; 108:103629.^,113113 Aggarwal N, Dwarakanathan V, Gautam N, Ray A. Facemasks for prevention of viral respiratory infections in community settings: A systematic review and meta-analysis. Indian J Public Health 2020; 64(Supl.):S192-S200..

Evidence of the use of cloth masks to prevent COVID-19 in Brazil

In Brazil, an evaluation of online search patterns showed a peak in interest regarding coronavirus in the country on March 21 and considerable interest by the Brazilian population regarding the use of masks shortly after publication of the Ministry of Health guidelines¹¹⁵115 Filho C, Vieira LJES, Silva RM. Buscas na internet sobre medidas de enfrentamento à COVID-19 no Brasil: descrição de pesquisas realizadas nos primeiros 100 dias de 2020. Epidemiol Serv Saúde 2020; 29(3):e2020191..

The first two states of Brazil to officially require the use of masks in public spaces as an additional measure against the virus were Pará and Santa Catarina on April 16, followed by Minas Gerais, Amapá and Goiás⁸8 Brasil. Ministério da Saúde (MS). Nota Técnica: Uso de máscaras caseiras. Brasília: MS; 2020. (Table 2). Already devastated by the pandemic, the state capital cities of Manaus and Rio de Janeiro did likewise by issuing municipal decrees on April 14 and April 18, respectively. Figure 5 shows the Brazilian states according to the month in which the obligatory use of masks in public spaces was officially decreed.

At federal level, the proposed bill number 1,562/2020, which made the use of masks obligatory in public spaces and in private spaces accessible to the public throughout the country for the duration of the state of calamity instituted due to the pandemic, was approved by congress on June 9 and referred for sanctioning by the president¹³⁹139 Senado Federal. Bolsonaro veta uso obrigatório de máscara no comércio, em escolas e em igrejas [Internet]. Senado Notícias; 2020 [acessado 2020 Jul 11]. Disponível em: https://www12.senado.leg.br/noticias/materias/2020/07/03/bolsonaro-veta-uso-obrigatorio-de-mascara-no-comercio-em-escolas-e-em-igrejas
https://www12.senado.leg.br/noticias/mat... . However, the president only sanctioned Law number 14,019 on July 2, 2020¹⁴⁰140 Brasil. Lei nº 14.019, de 2 de julho de 2020. Altera a Lei nº 13.979, de 6 de fevereiro de 2020, para dispor sobre a obrigatoriedade do uso de máscaras de proteção individual para circulação em espaços públicos e privados acessíveis ao público, em vias públicas e em transportes públicos, sobre a adoção de medidas de assepsia de locais de acesso público, inclusive transportes públicos, e sobre a disponibilização de produtos saneantes aos usuários durante a vigência das medidas para enfrentamento da emergência de saúde pública de importância internacional decorrente da pandemia da Covid-19. Diário Oficial da União 2020; 8 set. by which time all the states in Brazil except for the state of Rio de Janeiro already required the use of masks in public spaces. Furthermore, the president vetoed important parts of the proposed bill such as the use of masks in public offices and buildings and in commercial and industrial establishments, religious temples, teaching institutes and other indoor spaces in which people gather. The presidency also excluded from the proposed bill the clause that increased fines for repeat offenders and those not wearing a mask in enclosed spaces¹³⁹139 Senado Federal. Bolsonaro veta uso obrigatório de máscara no comércio, em escolas e em igrejas [Internet]. Senado Notícias; 2020 [acessado 2020 Jul 11]. Disponível em: https://www12.senado.leg.br/noticias/materias/2020/07/03/bolsonaro-veta-uso-obrigatorio-de-mascara-no-comercio-em-escolas-e-em-igrejas
https://www12.senado.leg.br/noticias/mat... . In accordance with the text that was sanctioned, establishments will also not be obliged to supply masks free of charge to their employees and neither will the authorities be obliged to provide masks to populations in a situation of socioeconomic vulnerability, contrary to what was stipulated in the original bill. It is important to emphasize that supplying masks to vulnerable populations or even to the entire population of cities or regions is a measure that has already been adopted by the governments of other nations⁶⁶66 Parry J. Covid-19: Hong Kong government supplies reusable face masks to all residents. BMJ 2020; 369:m1880. and in some Brazilian states such as Bahia, for example. For these and other reasons, the Brazilian government has been held up as an example of how not to proceed during a health crisis.

In the Brazilian context, the use of cloth masks as an additional protective measure against the COVID-19 pandemic is particularly relevant for socially vulnerable populations in view of the impossibility of adopting social distancing measures in various settings, e.g. in peripheral areas and slums and on public transport³⁴34 Zhou Z-G, Yue D-S, Mu C-L, Zhang L. Mask is the possible key for self-isolation in COVID-19 pandemic. J Med Virol 2020; 10.1002/jmv.25846.
https://doi.org/10.1002/jmv.25846... ^,3939 Gandhi M, Havlir D. The Time for Universal Masking of the Public for Coronavirus Disease 2019 Is Now. Open Forum Infect Dis 2020; 7(4):ofaa131.^,4040 Cheng KK, Lam TH, Leung CC. Wearing face masks in the community during the COVID-19 pandemic: altruism and solidarity. Lancet 2020; S0140-6736(20)30918-1 .^,4242 Cowling BJ, Ali ST, Ng TWY, Tsang TK, Li JCM, Fong MW, Liao Q, Kwan MY, Lee SL, Chiu SS, Wu JT, Wu P, Leung GM. Impact assessment of non-pharmaceutical interventions against coronavirus disease 2019 and influenza in Hong Kong: an observational study. Lancet Public Health 2020; ;5(5):e279-e288 .^,4646 Eikenberry SE, Mancuso M, Iboi E, Phan T, Eikenberry K, Kuang Y, Kostelich E, Gumel AB. To mask or not to mask: Modeling the potential for face mask use by the general public to curtail the COVID-19 pandemic. Infect Dis Model 2020; 5:293-308.^,5959 Ngonghala CN, Iboi E, Eikenberry S, Scotch M, MacIntyre CR, Bonds MH, Gumel AB. Mathematical assessment of the impact of non-pharmaceutical interventions on curtailing the 2019 novel Coronavirus. Math Biosci 2020; 325:108364.. In general, when resources are scarce, provision of masks should be strategic, and prioritize at-risk groups, as well as suspected and confirmed cases of infection, to optimize the protective effect at population level³³33 Worby CJ, Chang H-H. Face mask use in the general population and optimal resource allocation during the COVID-19 pandemic. Nat Commun 2020; 11(1):4049.. On the other hand, we highlight the need to take into consideration the potential effects of adoption of this protective measure for certain segments of the population such as when singling out certain age groups, ethnicities or races. Specifically, we would like to draw attention to the possibility that the widespread use of masks by the black population exposes this social group to greater harassment from the police and to situations of prejudice and racial discrimination¹⁴¹141 CNN. Why some people of color say they won't wear homemade masks [Internet]. 2020 [acessado 2020 Maio 4]. Disponível em: https://www.cnn.com/2020/04/07/us/face-masks-ethnicity-coronavirus-cdc-trnd/index.html
https://www.cnn.com/2020/04/07/us/face-m... ; and that the widespread use of masks hampers non-verbal communication with groups with an already diminished ability to communicate such as the deaf and/or dumb¹⁴²142 Martin V. Uso de máscaras prejudica comunicação dos surdos [Internet]. pleno.news 2020 [acessado 2020 Maio 4]. Disponível em: https://pleno.news/comportamento/pandemia-uso-de-mascaras-afeta-comunicacao-de-pessoas-surdas.html
https://pleno.news/comportamento/pandemi... .

Discussion

This narrative synthesis shows the rapid progress made in the acquisition of knowledge and the changes that have occurred in perceptions regarding this additional means of containing SARS-CoV-2 transmission, highlighting not only the prolific scientific contribution during the pandemic but also how COVID-19 has challenged the limits of knowledge. The large number of articles published daily and the low quality of many of these studies on this theme alongside the absence of observational studies about the correct use of masks, reveal the difficulties to produce scientific reviews in this moment when publications are increasing exponentially.

In face of the course of the pandemic and the evidence accumulated over recent months, the recommendation regarding the widespread use of cloth masks in public has been highlighted as an important strategy to: i) reduce the spread of the novel coronavirus²⁶26 Leung CC, Lam TH, Cheng KK. Let us not forget the mask in our attempts to stall the spread of COVID-19. Int J Tuberc Lung Dis 2020; 24(4):364-366.^,2929 Leung CC, Lam TH, Cheng KK. Mass masking in the COVID-19 epidemic: people need guidance. Lancet 2020; 395(10228):945.^,3535 Javid B, Weekes MP, Matheson NJ. Covid-19: should the public wear face masks? BMJ 2020; 369:m1442.^,3939 Gandhi M, Havlir D. The Time for Universal Masking of the Public for Coronavirus Disease 2019 Is Now. Open Forum Infect Dis 2020; 7(4):ofaa131.^,4040 Cheng KK, Lam TH, Leung CC. Wearing face masks in the community during the COVID-19 pandemic: altruism and solidarity. Lancet 2020; S0140-6736(20)30918-1 .^,4242 Cowling BJ, Ali ST, Ng TWY, Tsang TK, Li JCM, Fong MW, Liao Q, Kwan MY, Lee SL, Chiu SS, Wu JT, Wu P, Leung GM. Impact assessment of non-pharmaceutical interventions against coronavirus disease 2019 and influenza in Hong Kong: an observational study. Lancet Public Health 2020; ;5(5):e279-e288 .^,4646 Eikenberry SE, Mancuso M, Iboi E, Phan T, Eikenberry K, Kuang Y, Kostelich E, Gumel AB. To mask or not to mask: Modeling the potential for face mask use by the general public to curtail the COVID-19 pandemic. Infect Dis Model 2020; 5:293-308.^,4848 Garcia LP. Use of facemasks to limit COVID-19 transmission. Epidemiol Serv Saude 2020; 29(2):e2020023.^,5151 Cho-Han Chiang, Cho-Hung Chiang, Cho-Hsien Chiang, Yee-Chun Chen. The Practice of Wearing Surgical Masks during the COVID-19 Pandemic. Emerg Infect Dis 2020; 26(8):1962.^,5454 Konda A, Prakash A, Moss GA, Schmoldt M, Grant GD, Guha S. Aerosol Filtration Efficiency of Common Fabrics Used in Respiratory Cloth Masks. ACS Nano 2020; 14(5):6339-6347.

55 Victor CWT, Shing YT, Wai KP, Helen KWL, Shara WYL. A reality check on the use of face masks during the COVID-19 outbreak in Hong Kong. EClinicalMedicine 2020; 22:100356.^-5656 Wu E, Qi D. Masks and thermometers: Paramount measures to stop the rapid spread of SARS-CoV-2 in the United States. Genes Dis 2020; 10.1016/j.gendis.2020.04.011.
https://doi.org/10.1016/j.gendis.2020.04... ^,5858 Sunjaya AP, Jenkins C. Rationale for universal face masks in public against COVID-19. Respirology 2020; 5(7):678-679.^,5959 Ngonghala CN, Iboi E, Eikenberry S, Scotch M, MacIntyre CR, Bonds MH, Gumel AB. Mathematical assessment of the impact of non-pharmaceutical interventions on curtailing the 2019 novel Coronavirus. Math Biosci 2020; 325:108364.^,135135 Brooks JT, Butler JC, Redfield RR. Universal Masking to Prevent SARS-CoV-2 Transmission-The Time Is Now. JAMA 2020; 10.1001/jama.2020.13107.
https://doi.org/10.1001/jama.2020.13107... ; ii) reduce the possibility that disposable masks could be discarded inappropriately, resulting in a secondary source of infection of the disease²⁰20 Wang M-W, Zhou M-Y, Ji G-H, Ye L, Cheng Y-R, Feng Z-H, Chen J. Mask crisis during the COVID-19 outbreak. Eur Rev Med Pharmacol Sci 2020; 24(6):3397-3399.^,7272 Ogoina D. COVID-19: The Need for Rational Use of Face Masks in Nigeria. Am J Trop Med Hyg 2020; 103(1):33-34.^,122122 Bamber JH, Christmas T. Covid-19: Each discarded face mask is a potential biohazard. BMJ 2020; 369:m2012.; and iii) help contain the transmission of other infectious/contagious diseases such as influenza⁴²42 Cowling BJ, Ali ST, Ng TWY, Tsang TK, Li JCM, Fong MW, Liao Q, Kwan MY, Lee SL, Chiu SS, Wu JT, Wu P, Leung GM. Impact assessment of non-pharmaceutical interventions against coronavirus disease 2019 and influenza in Hong Kong: an observational study. Lancet Public Health 2020; ;5(5):e279-e288 .^,7474 Noh JY, Seong H, Yoon JG, Song JY, Cheong HJ, Kim WJ. Social Distancing against COVID-19: Implication for the Control of Influenza. J Korean Med Sci 2020; 35(19):e182.^,8585 Lee H, Lee H, Song K-H, Kim ES, Park JS, Jung J, Ahn S, Jeong EK, Park H, Kim HB. Impact of Public Health Interventions on Seasonal Influenza Activity During the SARS-CoV-2 Outbreak in Korea. Clin Infect Dis 2020; ciaa672.^,143143 Chow A, Hein AA, Kyaw WM. Unintended Consequence: Influenza plunges with public health response to COVID-19 in Singapore. J Infect 2020; 81(2):e68-e69.; reducing the burden of disease in the population, avoiding overwhelming the healthcare system and guaranteeing better healthcare for those who need it.

Therefore, widespread adoption of the use of cloth masks can also be considered an example of civic duty. It is a minor effort and a highly effective, low technology solution that can change the epidemiological trajectory of countries, improving national and global efforts to combat COVID-19¹³⁵135 Brooks JT, Butler JC, Redfield RR. Universal Masking to Prevent SARS-CoV-2 Transmission-The Time Is Now. JAMA 2020; 10.1001/jama.2020.13107.
https://doi.org/10.1001/jama.2020.13107... .

This literature review allowed us to evaluate at national and international levels the importance of adopting cloth masks as an additional measure to prevent the transmission of SARS-CoV-2. Despite its broad scope, this review has a few limitations. First, the narrative review can be criticized by its less rigid structure, when compare to systematic and integrative reviews. Nevertheless, it is an adequate alternative to identify gaps in the literature and to critically explore understudied themes¹⁴⁴144 Jesson J, Matheson L, Lacey FM. Doing Your Literature Review: Traditional and Systematic Techniques. Thousand Oaks: Sage Publications; 2011., and has the advantage that it could be completed in a short time, which matches the urgency of the theme. Second, the inclusion of pre-print manuscripts (such as the MedRxiv bibliographic database) that have not yet been peer reviewed can also be questioned, yet their inclusion was important in this manuscript as they too contributed to informing recommendations during the pandemic.

Evidence accumulated over the few months of this epidemic supports the hypothesis that the widespread use of cloth masks in public spaces represents a promising public health intervention that, in association with the preventive measures of social distancing and hand-washing, contributes towards decelerating the spread of COVID-19, reducing the number of cases and the number of deaths. This evidence has been rapidly reflected in public policies as an increasing number of countries began to adopt the obligatory use of masks in public spaces. A study conducted in Germany showed that the use of masks was perceived by society as a social contract and that the mandatory use of masks was seen as more just than relying on voluntary use¹⁴⁵145 Betsch C, Korn L, Sprengholz P, Felgendreff L, Eitze S, Schmid P, Böhm R. Social and behavioral consequences of mask policies during the COVID-19 pandemic. Proc Natl Acad Sci USA 2020; 117(36):21851-21853.. Many understood that the existing evidence already provides enough elements for an action based on the precautionary principle. In this specific case, this is an intervention that has the potential to be highly effective with a low risk of adverse effects¹⁴⁶146 Greenhalgh T. Face coverings for the public: Laying straw men to rest. J Eval Clin Pract 2020; 26(4):1070-1077..

In Brazil, where there is a shortage of disposable masks, where the capacity to test and screen suspected cases is limited and there is major urban overcrowding, with many homes lacking water supply and also being overcrowded, the use of cloth masks could be even more relevant in combatting the spread of the disease. Their use becomes essential, particularly in view of the slackening of social distancing measures and the implementation of strategies to promote a gradual return to activities⁴⁰40 Cheng KK, Lam TH, Leung CC. Wearing face masks in the community during the COVID-19 pandemic: altruism and solidarity. Lancet 2020; S0140-6736(20)30918-1 .^,4747 Thomson GA. COVID-19: Leaving lockdown-Of Schrodinger, cats, testing and masks. Int J Clin Pract 2020; 74(8):e13519.^,147147 Instituto Brasileiro de Geografia e Estatística (IBGE). Síntese de indicadores sociais: uma análise das condições de vida da população brasileira: 2019 [Internet]. 2019 [acessado 2020 Maio 2]. Disponível em: https://biblioteca.ibge.gov.br/index.php/biblioteca-catalogo? view=detalhes&id=2101678
https://biblioteca.ibge.gov.br/index.php... , which have already begun to be discussed and implemented by public authorities despite the fact that the pandemic continues to ravage the country. The current previsions for post-pandemic scenarios suggest that the use of cloth masks in public spaces will constitute an important measure in slowing down a possible second wave of infection⁶¹61 Hoertel N, Blachier M, Blanco C, Olfson M, Massetti M, Rico MS, Limosin F, Leleu H. Lockdown exit strategies and risk of a second epidemic peak: a stochastic agent-based model of SARS-CoV-2 epidemic in France. medRxiv 2020; 10.1101/2020.04.30.20086264.
https://doi.org/10.1101/2020.04.30.20086... ^,7878 Goscé L, Phillips PA, Spinola P, Gupta DRK, Abubakar PI. Modelling SARS-COV2 Spread in London: Approaches to Lift the Lockdown. J Infect 2020; 81(2):260-265.. Furthermore, educational actions aimed at promoting the correct use of cloth masks as a new social norm are also required³⁵35 Javid B, Weekes MP, Matheson NJ. Covid-19: should the public wear face masks? BMJ 2020; 369:m1442.^,9090 Goh Y, Tan BYQ, Bhartendu C, Ong JJY, Sharma VK. The face mask: How a real protection becomes a psychological symbol during Covid-19? Brain Behav Immun 2020; 88:1-5..

Therefore, coordinated actions are required from the public authorities to: i) support or develop strategies to increase production of masks and ensure their distribution to the public, including via donation to more vulnerable groups and those with fewer resources, as well as permitting the sale of masks in commercial establishments that are allowed to stay open during the pandemic; ii) encourage and increase the domestic production of cloth masks and production by self-employed seamstresses, guaranteeing fair working conditions, pay and health protection; and iii) guarantee that racial groups and socioeconomically deprived segments of the population are not stigmatized with the adoption of compulsory requirements to wear masks in public spaces.

Conclusion

Widespread use of cloth masks in public spaces is an effective health intervention when combined with social distancing and hand washing, and it has been adopted at greater or smaller scales across all continents with the advance of the pandemic throughout the world as it can contribute to reduce the transmission rates of SARS-CoV-2.

Cloth masks represent a cheaper, logistically viable option and one that is accessible to the general population, as well as being environmentally sustainable and an option that helps avoid depleting stocks of professional masks.

Acknowledgments

All authors are collaborators of the Co-Vida Network and thank the Evidence Synthesis Group for the discussions. We thank Jessyca Teixeira for her help in preparing the maps. Luciana Leite thanks the postdoctoral scholarship financed by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - Brazil (CAPES) - Financing Code 001.

References

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