The science around the use of masks by the public to impede COVID-19 transmission is advancing rapidly. In this narrative review, we develop an analytical framework to examine mask usage, synthesizing the relevant literature to inform multiple areas: population impact, transmission characteristics, source control, wearer protection, sociological considerations, and implementation considerations. A primary route of transmission of COVID-19 is via respiratory particles, and it is known to be transmissible from presymptomatic, paucisymptomatic, and asymptomatic individuals. Reducing disease spread requires two things: limiting contacts of infected individuals via physical distancing and other measures and reducing the transmission probability per contact. The preponderance of evidence indicates that mask wearing reduces transmissibility per contact by reducing transmission of infected respiratory particles in both laboratory and clinical contexts. Public mask wearing is most effective at reducing spread of the virus when compliance is high. Given the current shortages of medical masks, we recommend the adoption of public cloth mask wearing, as an effective form of source control, in conjunction with existing hygiene, distancing, and contact tracing strategies. Because many respiratory particles become smaller due to evaporation, we recommend increasing focus on a previously overlooked aspect of mask usage: mask wearing by infectious people ("source control") with benefits at the population level, rather than only mask wearing by susceptible people, such as health care workers, with focus on individual outcomes. We recommend that public officials and governments strongly encourage the use of widespread face masks in public, including the use of appropriate regulation.

Anesthesia Informatics and Media Lab School of Medicine Stanford University Stanford CA 94305

Center for Quantitative Biology Peking University Beijing 100871 China

Complex Systems Division Beijing Computational Science Research Center Beijing 100193 China

Data Institute University of San Francisco San Francisco CA 94105

Data Umbrella New York NY 10031

Department of Aeronautics and Astronautics Massachusetts Institute of Technology Cambridge MA 02139

Department of Biostatistics Jonathan and Karin Fielding School of Public Health University of California Los Angeles CA 90095

Department of Epidemiology Jonathan and Karin Fielding School of Public Health University of California Los Angeles CA 90095

Department of Information Systems Business Statistics and Operations Management Hong Kong University of Science and Technology Hong Kong SAR China

Department of Physics Hong Kong Baptist University Hong Kong SAR China

Department of Primary Health Care Sciences University of Oxford Oxford OX2 6GG United Kingdom

fast ai San Francisco CA 94105;

Institute of Chemical Process Fundamentals Czech Academy of Sciences CZ 165 02 Praha 6 Czech Republic

OpenAI San Francisco CA 94110

Perelman School of Medicine University of Pennsylvania Philadelphia PA 19104

School of Information University of North Carolina at Chapel Hill Chapel Hill NC 27599

School of Public Health and Family Medicine University of Cape Town Cape Town 7925 South Africa

TB Proof Cape Town 7130 South Africa

Teacher Education Department Vrije Universiteit Brussel 1050 Brussels Belgium

Warren Alpert School of Medicine Brown University Providence RI 02903

Komentář v

Lancet. 2022 Apr 30;399(10336):e39-e40. doi: 10.1016/S0140-6736(20)30918-1. PubMed

Erratum v

Proc Natl Acad Sci U S A. 2024 Apr 30;121(18):e2314762120. doi: 10.1073/pnas.2314762120. PubMed

Zobrazit více v PubMed

Wang Q., Yu C., Letter to editor: Role of masks/respirator protection against 2019-novel coronavirus (COVID-19). Infect. Contr. Hosp. Epidemiol. 1, 1–7 (2020). PubMed PMC

Feng S., et al. , Rational use of face masks in the COVID-19 pandemic. Lancet Respir. Med. 8, 434–436 (2020). PubMed PMC

Goh L. G., Ho T., Phua K. H., Wisdom and western science: The work of Dr Wu Lien-Teh. Asia Pac. J. Publ. Health 1, 99–109 (1987). PubMed

Wu L. T., A Treatise on Pneumonic Plague (League of Nations, Health Organization, 1926), pp. 373–398.

Cowling B. J., et al. , Impact assessment of non-pharmaceutical interventions against coronavirus disease 2019 and influenza in Hong Kong: An observational study. Lancet Public Health 5, E279-E288 (2020). PubMed PMC

What countries require masks in public or recommend masks? https://masks4all.co/what-countries-require-masks-in-public/. Accessed 26 June 2020.

Higgins J. P., et al. , Cochrane Handbook for Systematic Reviews of Interventions (John Wiley, 2019). PubMed

World Health Organization , Handbook for Guideline Development (World Health Organization, 2010).

Greenhalgh T., Face coverings for the public: Laying straw men to rest. J. Eval. Clin. Pract. 1, e13415 (2020). PubMed PMC

Wang Y., et al. , Reduction of secondary transmission of SARS-CoV-2 in households by face mask use, disinfection and social distancing: A cohort study in Beijing, China. BMJ Global Health 5, e002794 (2020). PubMed PMC

Chu D. K., et al. , 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 395, P1973–P1987 (2020). PubMed PMC

Tuan P., et al. , SARS transmission in Vietnam outside of the health-care setting. Epidemiol. Infect. 135, 392–401 (2007). PubMed PMC

Wu J., et al. , Risk factors for SARS among persons without known contact with SARS patients, Beijing, China. Emerg. Infect. Dis. 10, 210–216 (2004). PubMed PMC

MacIntyre C. R., et al. , The first randomized, controlled clinical trial of mask use in households to prevent respiratory virus transmission. Int. J. Infect. Dis. 12, e328 (2008).

Jefferson T., et al. , Physical interventions to interrupt or reduce the spread of respiratory viruses. Cochrane Database Syst. Rev. 7, CD006207 (2011). PubMed PMC

Jefferson T., et al. , Physical interventions to interrupt or reduce the spread of respiratory viruses. Part 1 - Face masks, eye protection and person distancing: Systematic review and meta-analysis. 10.1101/2020.03.30.20047217 (7 April 2020). DOI

MacIntyre C. R., Chughtai A. A., 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. 1, 103629 (2020). PubMed PMC

The University of Edinburgh Usher Institute , Summary: Does the use of face masks in the general population make a difference to spread of infection? https://www.ed.ac.uk/files/atoms/files/uncover_003-03_summary_-_facemasks_community_anon.pdf. Accessed 10 June 2020.

GUPTA M., Gupta K., Gupta S., The use of facemasks by the general population to prevent transmission of Covid 19 infection: A systematic review. 10.1101/2020.05.01.20087064 (6 May 2020). DOI

Brainard J. S., Jones N., Lake I., Hooper L., Hunter P., Facemasks and similar barriers to prevent respiratory illness such as COVID-19: A rapid systematic review. 10.1101/2020.04.01.20049528 (6 April 2020). PubMed DOI PMC

Suess T., et al. , The role of facemasks and hand hygiene in the prevention of influenza transmission in households: Results from a cluster randomised trial; Berlin, Germany, 2009–2011. BMC Infect. Dis. 12, 26 (2012). PubMed PMC

Cowling B. J., et al. , Facemasks and hand hygiene to prevent influenza transmission in households: A cluster randomized trial. Ann. Intern. Med. 151, 437–446 (2009). PubMed

Aiello A. E., et al. , Mask use, hand hygiene, and seasonal influenza-like illness among young adults: A randomized intervention trial. J. Infect. Dis. 201, 491–498 (2010). PubMed

Aiello A. E., et al. , Facemasks, hand hygiene, and influenza among young adults: A randomized intervention trial. PloS One 7, e29744 (2012). PubMed PMC

MacIntyre C. R., et al. , A cluster randomised trial of cloth masks compared with medical masks in healthcare workers. BMJ Open 5, e006577 (2015). PubMed PMC

Ogilvie D., et al. , Using natural experimental studies to guide public health action: Turning the evidence-based medicine paradigm on its head. J. Epidemiol. Community Health 74, 203–208 (2020). PubMed PMC

Greenhalgh T., Thorne S., Malterud K., Time to challenge the spurious hierarchy of systematic over narrative reviews? Eur. J. Clin. Invest. 48, e12931 (2018). PubMed PMC

World Commission on the Ethics of Scientific Knowledge and Technology , The Precautionary Principle (United Nations Educational, Scientific and Cultural Organization, 2005).

Leffler C. T., et al. , Association of country-wide coronavirus mortality with demographics, testing, lockdowns, and public wearing of masks. Am. J. Trop. Med. Hyg. 103, 2400–2411 (2020). PubMed PMC

Kenyon C., Widespread use of face masks in public may slow the spread of SARS CoV-2: An ecological study. 10.1101/2020.03.31.20048652 (6 April 2020). DOI

Lyu W., Wehby G. L., Community use of face masks and COVID-19: Evidence from a natural experiment of state mandates in the US. Health Aff. 39, 1419–1425 (2020). PubMed

Hatzius J., Struyven D., Rosenbery I., Face masks and GDP. https://www.goldmansachs.com/insights/pages/face-masks-and-gdp.html. Accessed 3 July 2020.

Wong S. H., et al. , COVID-19 and public interest in face mask use. Am. J. Respir. Crit. Care Med. 202, 453–455 (2020). PubMed PMC

Abaluck J., et al. , The case for universal cloth mask adoption and policies to increase supply of medical masks for health workers. 10.2139/ssrn.3567438 (6 April 2020). DOI

Cheng V. C., et al. , 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. 81, 107–114 (2020). PubMed PMC

He W., Yi G. Y., Zhu Y., Estimation of the basic reproduction number, average incubation time, asymptomatic infection rate, and case fatality rate for COVID-19: Meta-analysis and sensitivity analysis. J. Med. Virol. 92, 2543–2550 (2020). PubMed PMC

Stutt R. O., Retkute R., Bradley M., Gilligan C. A., Colvin J., A modeling framework to assess the likely effectiveness of facemasks in combination with ‘lock-down’in managing the COVID-19 pandemic. Proc. R. Soc. Lond. A 476, 20200376 (2020). PubMed PMC

Kai D., Goldstein G. P., Morgunov A., Nangalia V., Rotkirch A., Universal masking is urgent in the COVID-19 pandemic: SEIR and agent based models, empirical validation, policy recommendations. arXiv:2004.13553v1 (22 April 2020).

Tian L., et al. , Calibrated intervention and containment of the COVID-19 pandemic. arXiv:2003.07353v4 (2 April 2020).

Ferguson N., et al. , “Impact of non-pharmaceutical interventions (NPIs) to reduce COVID19 mortality and healthcare demand” (Rep. 9, The Royal Society, 2020). PubMed PMC

Ngonghala C. N., et al. , Mathematical assessment of the impact of non-pharmaceutical interventions on curtailing the 2019 novel coronavirus. Math. Biosci. 1, 108364 (2020). PubMed PMC

Yan J., Guha S., Hariharan P., Myers M., Modeling the effectiveness of respiratory protective devices in reducing influenza outbreak. Risk Anal. 39, 647–661 (2019). PubMed

Fisman D. N., Greer A. L., Tuite A. R., Brief research report: Bidirectional impact of imperfect mask use on reproduction number of COVID-19: A next generation matrix approach. Infect. Dis. Model. 5, 405–408 (2020). PubMed PMC

Lauer S. A., et al. , The incubation period of coronavirus disease 2019 (COVID-19) from publicly reported confirmed cases: Estimation and application. Ann. Intern. Med., 172, 577–582 (2020). PubMed PMC

To K. K. W., et al. , Temporal profiles of viral load in posterior oropharyngeal saliva samples and serum antibody responses during infection by SARS-CoV-2: An observational cohort study. Lancet Infect. Dis. 20, P565–P574 (2020). PubMed PMC

Zou L., et al. , SARS-CoV-2 viral load in upper respiratory specimens of infected patients. N. Engl. J. Med. 382, 1177–1179 (2020). PubMed PMC

Wölfel R., et al. , Virological assessment of hospitalized patients with COVID-2019. Nature 581, 465–469 (2020). PubMed

Oran D. P., Topol E. J., Prevalence of asymptomatic SARS-CoV-2 infection: A narrative review. Ann. Intern. Med. 173, 363–367 (2020). PubMed PMC

Jones T. C., et al. , An analysis of SARS-CoV-2 viral load by patient age. 10.1101/2020.06.08.20125484 (9 June 2020). DOI

Han M., et al. , Viral RNA load in mildly symptomatic and asymptomatic children with COVID-19, Seoul. Emerg. Infect. Dis. 26, 2497–2499 (2020). PubMed PMC

Bourouiba L., Turbulent gas clouds and respiratory pathogen emissions: Potential implications for reducing transmission of COVID-19. J. Am. Med. Assoc. 323, 1837–1838 (2020). PubMed

Milton D. K., A Rosetta Stone for understanding infectious drops and aerosols. J. Pediatric. Infect. Dis. Soc. 9, 413–415 (2020). PubMed PMC

Asadi S., et al. , Aerosol emission and superemission during human speech increase with voice loudness. Sci. Rep. 9, 2348 (2019). PubMed PMC

Stadnytskyi V., Bax C. E., Bax A., Anfinrud P., The airborne lifetime of small speech droplets and their potential importance in SARS-CoV-2 transmission. Proc. Natl. Acad. Sci. U.S.A. 117, 11875–11877 (2020). PubMed PMC

Wells W., On air-borne infection: Study II. Droplets and droplet nuclei. Am. J. Epidemiol. 20, 611–618 (1934).

Papineni R. S., Rosenthal F. S., The size distribution of droplets in the exhaled breath of healthy human subjects. J. Aerosol Med. 10, 105–116 (1997). PubMed

Duguid J., The size and the duration of air-carriage of respiratory droplets and droplet-nuclei. Epidemiol. Infect. 44, 471–479 (1946). PubMed PMC

Morawska L., et al. , Size distribution and sites of origin of droplets expelled from the human respiratory tract during expiratory activities. J. Aerosol Sci. 40, 256–269 (2009).

Anfinrud P., Stadnytskyi V., Bax C. E., Bax A., Visualizing speech-generated oral fluid droplets with laser light scattering. N. Engl. J. Med. 382, 2061–2063 (2020). PubMed PMC

Vuorinen V., et al. , Modeling aerosol transport and virus exposure with numerical simulations in relation to SARS-CoV-2 transmission by inhalation indoors. Saf. Sci. 130, 104866 (2020). PubMed PMC

Prather K. A., Wang C. C., Schooley R. T., Reducing transmission of SARS-CoV-2. Science 368, 1422–1424 (2020). PubMed

Gralton J., Tovey E., McLaws M. L., Rawlinson W. D., The role of particle size in aerosolized pathogen transmission: A review. J. Infect. 62, 1–13 (2011). PubMed PMC

Atkinson M. P., Wein L. M., Quantifying the routes of transmission for pandemic influenza. Bull. Math. Biol. 70, 820–867 (2008). PubMed

Ma J., et al. , Exhaled breath is a significant source of SARS-CoV-2 emission. 10.1101/2020.05.31.20115154 (2 June 2020). DOI

Yan J., et al. , Infectious virus in exhaled breath of symptomatic seasonal influenza cases from a college community. Proc. Natl. Acad. Sci. U.S.A. 115, 1081–1086 (2018). PubMed PMC

Brosseau L., et al. , “N95 respirators and surgical masks.” NIOSH Science Blog. https://blogs.cdc.gov/niosh-science-blog/2009/10/14/n95. Accessed 3 April 2020.

Leung N. H., et al. , Respiratory virus shedding in exhaled breath and efficacy of face masks. Nat. Med. 26, 676–680 (2020). PubMed PMC

Greene V., Vesley D., Method for evaluating effectiveness of surgical masks. J. Bacteriol. 83, 663–667 (1962). PubMed PMC

Quesnel L. B., The efficiency of surgical masks of varying design and composition. Br. J. Surg. 62, 936–940 (1975). PubMed PMC

Johnson D. F., Druce J. D., Birch C., Grayson M. L., A quantitative assessment of the efficacy of surgical and N95 masks to filter influenza virus in patients with acute influenza infection. Clin. Infect. Dis. 49, 275–277 (2009). PubMed

Milton D. K., Fabian M. P., Cowling B. J., Grantham M. L., McDevitt J. J., Influenza virus aerosols in human exhaled breath: Particle size, culturability, and effect of surgical masks. PLoS Pathog. 9, e1003205 (2013). PubMed PMC

Vanden Driessche K., et al. , Surgical masks reduce airborne spread of Pseudomonas aeruginosa in colonized patients with cystic fibrosis. Am. J. Respir. Crit. Care Med. 192, 897–899 (2015). PubMed

Wood M. E., et al. , Face masks and cough etiquette reduce the cough aerosol concentration of Pseudomonas aeruginosa in people with cystic fibrosis. Am. J. Respir. Crit. Care Med. 197, 348–355 (2018). PubMed

Stockwell R. E., et al. , Face masks reduce the release of Pseudomonas aeruginosa cough aerosols when worn for clinically relevant periods. Am. J. Respir. Crit. Care Med. 198, 1339–1342 (2018). PubMed

Dharmadhikari A. S., et al. , Surgical face masks worn by patients with multidrug-resistant tuberculosis: Impact on infectivity of air on a hospital ward. Am. J. Respir. Crit. Care Med. 185, 1104–1109 (2012). PubMed PMC

Chan J. F. W., et al. , Surgical mask partition reduces the risk of non-contact transmission in a golden Syrian hamster model for Coronavirus Disease 2019 (COVID-19). Clin. Infect. Dis. 71, 2139–2149 (2020). PubMed PMC

Davies A., et al. , Testing the efficacy of homemade masks: Would they protect in an influenza pandemic? Disaster Med. Public Health Prep. 7, 413–418 (2013). PubMed PMC

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 3, e2618 (2008). PubMed PMC

Viola I., et al. , Face coverings, aerosol dispersion and mitigation of virus transmission risk. arXiv:2005.10720v1 (19 May 2020). PubMed PMC

Kumar V., et al. , On the utility of cloth facemasks for controlling ejecta during respiratory events. arXiv:2005.03444v1 (5 May 2020).

Verma S., Dhanak M., Frankenfield J., Visualizing the effectiveness of face masks in obstructing respiratory jets. Phys. Fluids 32, 061708 (2020). PubMed PMC

Centers for Disease Control and Prevention , How coronavirus spreads. https://www.cdc.gov/coronavirus/2019-ncov/prevent-getting-sick/how-covid-spreads.html. Accessed 5 July 2020.

Goldman E., Exaggerated risk of transmission of COVID-19 by fomites. Lancet Infect. Dis. 20, 892–893 (2020). PubMed PMC

Ippolito M., Iozzo P., Gregoretti C., Grasselli G., Cortegiani A., Facepiece filtering respirators with exhalation valve should not be used in the community to limit SARS-CoV-2 diffusion. Infect. Contr. Hosp. Epidemiol. 15, 1–2 (2020). PubMed PMC

National Institute for Occupational Safety and Health , NIOSH guide to the selection and use of particulate respirators certified under 42 CFR 84 (96-101). https://www.cdc.gov/niosh/docs/96-101/default.html. Accessed 7 July 2020.

Jung H., et al. , Comparison of filtration efficiency and pressure drop in anti-yellow sand masks, quarantine masks, medical masks, general masks, and handkerchiefs. Aerosol. Air. Qual. Res. 14, 991–1002 (2013).

World Health Organization , “Advice on the use of masks in the context of COVID-19: Interim guidance, 5 June 2020” (Tech. Rep. WHO/2019-nCoV/IPC_Masks/2020.4, World Health Organization, 2020).

Zhao M., et al. , Household materials selection for homemade cloth face coverings and their filtration efficiency enhancement with triboelectric charging. Nano Lett. 20, 5544–5552 (2020). PubMed PMC

Konda A., et al. , Aerosol filtration efficiency of common fabrics used in respiratory cloth masks. ACS Nano 14, 6339–6347 (2020). PubMed

Dato V. M., Hostler D., Hahn M. E., Simple respiratory mask. Emerg. Infect. Dis. 12, 1033–1034 (2006). PubMed PMC

Runde D. P., et al. , The "double eights mask brace" improves the fit and protection of a basic surgical mask amidst COVID‐19 pandemic. J. Am. Coll. Emerg. Physicians Open, 10.1002/emp2.12335 (2020). PubMed PMC

Wilkes A. R., Benbough J. E., Speight S. E., Harmer M., The bacterial and viral filtration performance of breathing system filters. Anaesthesia 55, 458–465 (2000). PubMed

Long Y., et al. , Effectiveness of N95 respirators versus surgical masks against influenza: A systematic review and meta-analysis. J. Evid. Base Med. 13, 93–101 (2020). PubMed PMC

Radonovich L. J., et al. , N95 respirators vs medical masks for preventing influenza among health care personnel: A randomized clinical trial. J. Am. Med. Assoc. 322, 824–833 (2019). PubMed PMC

Bean B., et al. , Survival of influenza viruses on environmental surfaces. J. Infect. Dis. 146, 47–51 (1982). PubMed

Brosseau L. M., Sietsema M., Commentary: Masks-for-all for COVID-19 not based on sound data (Center for Infectious Disease Research and Policy, 2020). https://www.cidrap.umn.edu/news-perspective/2020/04/commentary-masks-all-covid-19-not-based-sound-data. Accessed 3 April 2020.

Cassell M. M., Halperin D. T., Shelton J. D., Stanton D., Risk compensation: The Achilles’ heel of innovations in HIV prevention? BMJ 332, 605–607 (2006). PubMed PMC

Rojas Castro D., Delabre R. M., Molina J. M., Give prep a chance: Moving on from the “risk compensation” concept. J. Int. AIDS Soc. 22, e25351 (2019). PubMed PMC

Ouellet J. V., Helmet use and risk compensation in motorcycle accidents. Traffic Inj. Prev. 12, 71–81 (2011). PubMed

Houston D. J., Richardson L. E., Risk compensation or risk reduction? Seatbelts, state laws, and traffic fatalities. Soc. Sci. Q. 88, 913–936 (2007).

Scott M. D., et al. , Testing the risk compensation hypothesis for safety helmets in alpine skiing and snowboarding. Inj. Prev. 13, 173–177 (2007). PubMed PMC

Peng Y., et al. , Universal motorcycle helmet laws to reduce injuries: A community guide systematic review. Am. J. Prev. Med. 52, 820–832 (2017). PubMed PMC

Ruedl G., Kopp M., Burtscher M., Does risk compensation undo the protection of ski helmet use? Epidemiology 23, 936–937 (2012). PubMed

Pless B., Risk compensation: Revisited and rebutted. Safety 2, 16 (2016).

Burgess A., Horii M., Risk, ritual and health responsibilisation: Japan’s ‘safety blanket’of surgical face mask-wearing. Sociol. Health Illness 34, 1184–1198 (2012). PubMed

Betsch C., et al. , Social and behavioral consequences of mask policies during the COVID-19 pandemic. Proc. Natl. Acad. Sci. U.S.A. 117, 21851–21853 (2020). PubMed PMC

Imperial College London , COVID-19 Behavior Tracker. http://coviddatahub.com/. Accessed 10 July 2020.

Chen Y. J., et al. , Comparison of face-touching behaviors before and during the coronavirus disease 2019 pandemic. JAMA Netw. Open 3, e2016924 (2020). PubMed

Seres G., et al. , Face masks increase compliance with physical distancing recommendations during the COVID-19 pandemic. https://epub.ub.uni-muenchen.de/74063/. Accessed 18 December 2020.

Marchiori M., COVID-19 and the social distancing paradox: Dangers and solutions. arXiv:2005.12446v1 (26 May 2020).

Seres G., Balleyer A. H., Cerutti N., Friedrichsen J., Süer M., Face mask use and physical distancing before and after mandatory masking: Evidence from public waiting lines. 10.2139/ssrn.3641367 (9 July 2020). PubMed DOI PMC

Joachim G., Acorn S., Stigma of visible and invisible chronic conditions. J. Adv. Nurs. 32, 243–248 (2000). PubMed

Abney K., “Containing” tuberculosis, perpetuating stigma: The materiality of N95 respirator masks. Anthropology Southern Africa 41, 270–283 (2018).

Buregyeya E., et al. , Acceptability of masking and patient separation to control nosocomial tuberculosis in Uganda: A qualitative study. J. Public Health 20, 599–606 (2012).

Li D. K., Abdelkader R., Coronavirus hate attack: Woman in face mask allegedly assaulted by man who calls her ’diseased.’ NBC News. https://www.nbcnews.com/news/us-news/coronavirus-hate-attack-woman-face-mask-allegedly-assaulted-man-who-n1130671. Accessed 10 April 2020.

Pager D., Shepherd H., The sociology of discrimination: Racial discrimination in employment, housing, credit, and consumer markets. Annu. Rev. Sociol. 34, 181–209 (2008). PubMed PMC

Fernando Alfonso C., III, Why some people of color say they won’t wear homemade masks. CNN. https://www.cnn.com/2020/04/07/us/face-masks-ethnicity-coronavirus-cdc-trnd/index.html. Accessed 9 April 2020.

Jan T., Two black men say they were kicked out of Walmart for wearing protective masks. Others worry it will happen to them. Washington Post, 9 April, 2020. https://www.washingtonpost.com/business/2020/04/09/masks-racial-profiling-walmart-coronavirus/. Accessed 10 April 2020.

Watson-Jones R. E., Legare C. H., The social functions of group rituals. Curr. Dir. Psychol. Sci. 25, 42–46 (2016).

BliegeBird R., et al. , Signaling theory, strategic interaction, and symbolic capital. Curr. Anthropol. 46, 221–248 (2005).

Van Houten R., Malenfant L., Huitema B., Blomberg R., Effects of high-visibility enforcement on driver compliance with pedestrian yield right-of-way laws. Transport. Res. Rec. 2393, 41–49 (2013).

Van Damme W., Van Lerberghe W., Editorial: Epidemics and fear. Trop. Med. Int. Health 5, 511–514 (2000). PubMed

Riva M. A., Benedetti M., Cesana G., Pandemic fear and literature: Observations from Jack London’s The Scarlet Plague. Emerg. Infect. Dis. 20, 1753–1757 (2014). PubMed PMC

Taal E., Rasker J. J., Seydel E. R., Wiegman O., Health status, adherence with health recommendations, self-efficacy and social support in patients with rheumatoid arthritis. Patient Educ. Counsel. 20, 63–76 (1993). PubMed

Illingworth P., Parmet W. E., Solidarity and health: A public goods justification. Diametros 43, 65–71 (2015).

Chen L. C., Evans T. G., Cash R. A. et al. , Health as a global public good. Global Public Goods 1, 284–304 (1999).

Cheng K. K., Lam T. H., Leung C. C., Wearing face masks in the community during the COVID-19 pandemic: Altruism and solidarity. Lancet 6736, 30918-1 (2020). PubMed PMC

Van Der Westhuizen H. M., Kotze K., Tonkin-crine S., Gobat N., Greenhalgh T., Face coverings for COVID-19: From medical intervention to social practice. BMJ 19, m3021 (2020). PubMed

The Lancet , COVID-19: Protecting health-care workers. Lancet 395, 922 (2020). PubMed PMC

Bartoszko J. J., Farooqi M. A. M., Alhazzani W., Loeb M., Medical masks vs N95 respirators for preventing COVID-19 in health care workers: A systematic review and meta-analysis of randomized trials. Influenza Other Respiratory Viruses 14, 365–373 (2020). PubMed PMC

de Man P., et al. , Sterilization of disposable face masks by means of standardized dry and steam sterilization processes: An alternative in the fight against mask shortages due to COVID-19. J Hosp Infect. 105, 356–357 (2020). PubMed PMC

Perencevich E. N., Diekema D. J., Edmond M. B., Moving personal protective equipment into the community: Face shields and containment of COVID-19. J. Am. Med. Assoc. 323, 2252–2253 (2020). PubMed

Larson E. L., et al. , Impact of non-pharmaceutical interventions on URIs and influenza in crowded, urban households. Publ. Health Rep. 125, 178–191 (2010). PubMed PMC

Leung G. M., et al. , A tale of two cities: Community psychobehavioral surveillance and related impact on outbreak control in Hong Kong and Singapore during the severe acute respiratory syndrome epidemic. Infect. Contr. Hosp. Epidemiol. 25, 1033–1041 (2004). PubMed

Cowling B. J., et al. , Community psychological and behavioral responses through the first wave of the 2009 influenza A (H1N1) pandemic in Hong Kong. J. Infect. Dis. 202, 867–876 (2010). PubMed

Bradford W. D., Mandich A., Some state vaccination laws contribute to greater exemption rates and disease outbreaks in the United States. Health Aff. 34, 1383–1390 (2015). PubMed

Chughtai A. A., et al. , Contamination by respiratory viruses on outer surface of medical masks used by hospital healthcare workers. BMC Infect. Dis. 19, 491 (2019). PubMed PMC

Kwong K., HKmask manual. https://diymask.site/. Accessed 6 July 2020.

Consumer Council Hong Kong , DIY face mask – 8 steps in making protective gear. https://www.consumer.org.hk/ws_en/news/specials/2020/mask-diy-tips.html. Accessed 8 April 2020.

Akduman C., Cellulose acetate and polyvinylidene fluoride nanofiber mats for N95 respirators. J. Ind. Textil., 10.1177/1528083719858760 (26 June 2019). DOI

van Doremalen N., et al. , Aerosol and surface stability of SARS-CoV-2 as compared with SARS-CoV-1. N. Engl. J. Med. 382, 1564–1567 (2020). PubMed PMC

High-quality and easy-to-regenerate personal filter

Unmasking the Mask: Investigating the Role of Physical Properties in the Efficacy of Fabric Masks to Prevent the Spread of the COVID-19 Virus

Commonly available but highly effective protection against SARS-CoV-2 during gastrointestinal endoscopies

A Review of Impact of Textile Research on Protective Face Masks