Update Alert 3: Masks for Prevention of Respiratory Virus Infections, Including SARS-CoV-2, in Health Care and Community Settings
Authors: Roger Chou, Tracy Dana, Rebecca Jungbauer, Chandler Weeks
Journal: Annals of Internal Medicine (2020)

Letters27 October 2020Update Alert 3: Masks for Prevention of Respiratory Virus Infections, Including SARS-CoV-2, in Health Care and Community SettingsFREERoger Chou, MD, Tracy Dana, MLS, Rebecca Jungbauer, DrPH, and Chandler Weeks, MPHRoger Chou, MDPacific Northwest Evidence-based Practice Center and Oregon Health & Science University, Portland, Oregon (R.C., T.D., R.J., C.W.)Search for more papers by this author, Tracy Dana, MLSPacific Northwest Evidence-based Practice Center and Oregon Health & Science University, Portland, Oregon (R.C., T.D., R.J., C.W.)Search for more papers by this author, Rebecca Jungbauer, DrPHPacific Northwest Evidence-based Practice Center and Oregon Health & Science University, Portland, Oregon (R.C., T.D., R.J., C.W.)Search for more papers by this author, and Chandler Weeks, MPHPacific Northwest Evidence-based Practice Center and Oregon Health & Science University, Portland, Oregon (R.C., T.D., R.J., C.W.)Search for more papers by this authorAuthor, Article, and Disclosure Informationhttps://doi.org/10.7326/L20-1292 SectionsSupplemental MaterialAboutVisual AbstractPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissions ShareFacebookTwitterLinkedInRedditEmail This is the third update alert for a living rapid review on the use of masks for prevention of respiratory virus infections, including severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), in health care and community settings (1). Searches were updated from 3 August to 2 October 2020 using the same search strategies as the original review. The updated searches identified 407 citations. One study (2) on the use of masks and SARS-CoV-2 infection in a community setting and 2 studies (3, 4) in health care settings were added (Supplement Tables 1 to 3).The evidence on mask use and risk for SARS-CoV-2 infection in community settings was previously assessed as insufficient on the basis of 1 study with methodological limitations (5). A new case–control study in Thailand enrolled asymptomatic contacts of patients with coronavirus disease 2019 (COVID-19) from 3 large community clusters (211 case patients and 839 uninfected control participants) (2). Wearing a mask all of the time versus no use was associated with decreased risk for SARS-CoV-2 infection after adjustment for age; sex; exposure to contact; sharing of dishes, cups, or cigarettes; and handwashing (adjusted odds ratio [OR], 0.23 [95% CI, 0.09 to 0.60]). However, inconsistent use was not associated with decreased risk (adjusted OR, 0.87 [CI, 0.41 to 1.84]). Mask type (medical mask only, nonmedical mask only, or both) was not independently associated with risk for SARS-CoV-2 infection (P = 0.54). Methodological limitations included potential recall bias. In addition, data were missing or had potential discrepancies, and control for exposures was limited. Therefore, the strength of evidence for mask use and risk for SARS-CoV-2 in community settings remained insufficient (Supplement Table 4).The evidence on mask use and risk for SARS-CoV-2 infection in health care settings was also previously assessed as insufficient on the basis of 1 study with methodological limitations (6). Two new studies reported on mask use in health care settings (3, 4). One cohort study (n = 903) of hospital health care workers in Italy exposed to a patient with COVID-19 reported an imprecise estimate, with no statistically significant difference between mask use (FFP2 or FFP3 [equivalent to N95 or N99] or surgical mask) versus no mask use and risk for COVID-19 (adjusted OR, 1.6 [CI, 0.9 to 2.9]). Use of an FFP2 or FFP3 mask versus a surgical mask was associated with increased risk for COVID-19 (adjusted OR, 7.1 [CI, 3.0 to 16.7]) (4). A case–control study of hospital physicians in Bangladesh (98 case patients with COVID-19 and 92 control participants) also reported an imprecise estimate for medical mask use versus no mask use and risk for COVID-19 (adjusted OR, 1.40 [CI, 0.30 to 6.42]). However, N95 mask use versus no mask use was associated with decreased risk for COVID-19 during aerosol-generating procedures (OR, 0.37 [CI, 0.16 to 0.87]) (3). Both studies had serious methodological limitations, including potential recall bias and data discrepancies. In addition, 1 study (4) controlled only for age, and it was unclear what confounders were controlled for in the other study (3). Therefore, evidence for mask use versus nonuse and comparing mask types in health care settings remained insufficient (Supplement Table 4). There were no new studies on the effectiveness and safety of mask reuse or extended use.References1. Chou R, Dana T, Jungbauer R, et al. Masks for prevention of respiratory virus infections, including SARS-CoV-2, in health care and community settings: a living rapid review. Ann Intern Med. 2020;173:542-555. doi:10.7326/M20-3213 LinkGoogle Scholar2. Doung-Ngern P, Suphanchaimat R, Panjangampatthana A, et al. Case-control study of use of personal protective measures and risk for SARS-CoV 2 infection, Thailand. Emerg Infect Dis. 2020;26:2607-2616. [PMID: 32931726] doi:10.3201/eid2611.203003 CrossrefMedlineGoogle Scholar3. Khalil MM, Alam MM, Arefin MK, et al. Role of personal protective measures in prevention of COVID-19 spread among physicians in Bangladesh: a multicenter cross-sectional comparative study. SN Compr Clin Med. 2020:1-7. [PMID: 32904377] doi:10.1007/s42399-020-00471-1 CrossrefMedlineGoogle Scholar4. Piapan L, De Michieli P, Ronchese F, et al. COVID-19 outbreak in healthcare workers in hospitals in Trieste, North-east Italy. J Hosp Infect. 2020. [PMID: 32805309] doi:10.1016/j.jhin.2020.08.012 CrossrefMedlineGoogle Scholar5. Wang Y, Tian H, Zhang L, 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 Glob Health. 2020. [PMID: 32467353] doi:10.1136/bmjgh-2020-002794 CrossrefMedlineGoogle Scholar6. Chatterjee P, Anand T, Singh KJ, et al. Healthcare workers & SARS-CoV-2 infection in India: a case-control investigation in the time of COVID-19. Indian J Med Res. 2020;151:459-467. [PMID: 32611916] doi:10.4103/ijmr.IJMR_2234_20 CrossrefMedlineGoogle Scholar Comments 0 Comments Sign In to Submit A Comment Jorge van ArckenClinical physician26 October 2020 Use or not use N95 Please, as long as the evidence can be sufficient, the use of N95 is necessary. Mitchel GalishoffValley Medical & Surgical Clinic, PC1 November 2020 1918 Influenza Pandemic I am reading some books on the 1918 pandemic. The same measures used in SanFrancisco are being used today. People were arrested for noncompliance. Although the number of deaths and newly infected people fell over the subsequent weeks, it was not as fast as predicted based upon the incubation time of the virus. The pattern was similar to that seen earlier in Boston and Philadelphia. The author mentions communities that had a strict mask and distancing programs that did not differ from places without them. The disease inexplicably spared many places and ravaged others. The only consistent pattern was a series of waves that took the lives of the most susceptible (in that case it included people in the prime of life). Crowded living conditions and the mobilization for war were key factors. Fatigue, noncompliance, resistance, and even civil disobedience prevented the full implementation of such measures over a long period and during subsequent waves. Demonstrating the efficacy of masks during the 1918 pandemic is problematic. It may be likewise today. We do not have adequate control populations nor do we have an ideal setting of full compliance with proper masks. One thing I am learning from reading the history of these epidemics is that it is more than a medical issue, i.e. more than a virus and patients. It is about the economy, politics, and social factors. A proper risk-benefit analysis must include all harms both direct and indirect. Epidemics, such as the one we are experiencing, are humbling in that they expose the limits of the promises of modernity. Our expectations may be higher than what is possible to achieve. Crosby, Alfred W, America's Forgotten Epidemic: The Influenza of 1918. Cambridge University Press, 2003 Author, Article, and Disclosure InformationAuthors: Roger Chou, MD; Tracy Dana, MLS; Rebecca Jungbauer, DrPH; Chandler Weeks, MPHAffiliations: Pacific Northwest Evidence-based Practice Center and Oregon Health & Science University, Portland, Oregon (R.C., T.D., R.J., C.W.)Disclaimer: The authors of this manuscript are responsible for its content. Statements in the manuscript do not necessarily represent the official views of or imply endorsement by the Agency for Healthcare Research and Quality or the U.S. Department of Health and Human Services.Disclosures: Disclosures can be viewed at www.acponline.org/authors/icmje/ConflictOfInterestForms.do?msNum=L20-1292.Corresponding Author: Roger Chou, MD, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Mail Code BICC, Portland, OR 97239; e-mail, chour@ohsu.edu.This article was published at Annals.org on 27 October 2020. PreviousarticleNextarticle Advertisement FiguresReferencesRelatedDetailsSee AlsoUpdate Alert: Masks for Prevention of Respiratory Virus Infections, Including SARS-CoV-2, in Health Care and Community Settings Roger Chou , Tracy Dana , Rebecca Jungbauer , Chandler Weeks , and Marian S. 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