Update Alert 5: 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 (2021)

Letters9 March 2021Update Alert 5: 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, OregonSearch for more papers by this author, Tracy Dana, MLSPacific Northwest Evidence-based Practice Center and Oregon Health & Science University, Portland, OregonSearch for more papers by this author, Rebecca Jungbauer, DrPHPacific Northwest Evidence-based Practice Center and Oregon Health & Science University, Portland, OregonSearch for more papers by this author, and Chandler Weeks, MPHPacific Northwest Evidence-based Practice Center and Oregon Health & Science University, Portland, OregonSearch for more papers by this authorAuthor, Article, and Disclosure Informationhttps://doi.org/10.7326/L21-0116 SectionsSupplemental MaterialAboutVisual AbstractPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissions ShareFacebookTwitterLinkedInRedditEmail This is the fifth update alert for a living rapid review on the use of masks for prevention of respiratory virus infections, including SARS-CoV-2, in health care and community settings (1). The first 3 updates were monthly, and the interval was switched to bimonthly for subsequent updates. Update searches were done from 3 December 2020 to 2 February 2021, using the same search strategies as the original review. The update searches identified 613 citations. Two studies (2, 3) on the use of masks and the prevention of SARS-CoV-2 were added for this update: 1 study (2) was done in a community setting, and the other (3) was done in a health care setting (Supplement Tables 1 to 3).On the basis of evidence from 1 randomized controlled trial (4) and 2 observational studies (5, 6), the strength of evidence for mask use versus nonuse for the prevention of SARS-CoV-2 in community settings was previously assessed as low for a small reduction in risk for infection with any mask use (Supplement Table 4). One new cross-sectional study done in Vermont reported an imprecise estimate for the association between wearing a mask (type unspecified) outside of a work environment or not wearing a mask and SARS-CoV-2 infection risk (odds ratio, 2.35 [95% CI, 0.67 to 8.25]) (Supplement Table 3) (2). Mask use was not included in multivariable models; in addition, the study had methodological limitations, including potential selection and recall bias and low participation and SARS-CoV-2 testing rates among eligible participants. Therefore, the strength of evidence for any mask use versus nonuse in community settings remains low (Supplement Table 4). Other strength-of-evidence ratings related to mask use in community settings were unchanged because of no new evidence.The evidence on various comparisons of mask use in health care settings and risk for SARS-CoV-2 infection was previously assessed as insufficient on the basis of 5 observational studies with methodological limitations (Supplement Table 4) (7–11). One new study done in 500 U.S. hospital workers in a high-prevalence area (SARS-CoV-2 seropositivity, 27%) was added for this update (3). In this study, only 2 hospital workers reported no mask use. Although the study evaluated N95 use only, surgical mask use only, or N95 and surgical mask use, analyses were of limited usefulness because the comparison group was any other mask use, including other types of masks or nonuse (for example, N95 only was compared with the combination of surgical mask only, N95 and surgical mask, or no mask use). In addition, estimates were imprecise, except for N95 and surgical mask use (odds ratio, 0.63 [CI, 0.41 to 1.0]). The comparison of N95 only versus surgical mask only favored the N95, but the difference was not statistically significant (odds ratio, 0.60 [CI, 0.31 to 1.15]). The study had methodological limitations, including no adjustment for confounders and potential recall and selection bias. On the basis of these limitations and because of inconsistent results across studies, evidence for N95 versus surgical mask use and other comparisons involving mask use and risk for SARS-CoV-2 infection in health care settings remains insufficient (Supplement Table 4).No new studies evaluated the effects of mask use and risk for SARS-CoV-1 infection, Middle East respiratory syndrome–CoV infection, or influenza or influenza-like illness. As with prior updates, 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. [PMID: 32579379]. doi:10.7326/M20-3213 LinkGoogle Scholar2. van den Broek-Altenburg EM, Atherly AJ, Diehl SA, et al. Jobs, housing, and mask wearing: cross-sectional study of risk factors for COVID-19. JMIR Public Health Surveill. 2021;7:e24320. [PMID: 33315576] doi:10.2196/24320 CrossrefMedlineGoogle Scholar3. Venugopal U, Jilani N, Rabah S, et al. SARS-CoV-2 seroprevalence among health care workers in a New York City hospital: a cross-sectional analysis during the COVID-19 pandemic. Int J Infect Dis. 2021;102:63-69. [PMID: 33075539] doi:10.1016/j.ijid.2020.10.036 CrossrefMedlineGoogle Scholar4. Bundgaard H, Bundgaard JS, Raaschou-Pedersen DET, et al. Effectiveness of adding a mask recommendation to other public health measures to prevent SARS-CoV-2 infection in Danish mask wearers: a randomized controlled trial. Ann Intern Med. 2020. [PMID: 33205991]. doi:10.7326/M20-6817 MedlineGoogle 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;5. [PMID: 32467353] doi:10.1136/bmjgh-2020-002794 CrossrefGoogle Scholar6. 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 Scholar7. 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 Scholar8. Piapan L, De Michieli, Ronchese F, et al. COVID-19 outbreak in healthcare workers in hospitals in Trieste, North-east Italy. J Hosp Infect. 2020;106:626-628. [PMID: 32805309] doi:10.1016/j.jhin.2020.08.012 CrossrefMedlineGoogle Scholar9. 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 MedlineGoogle Scholar10. Akinbami LJ, Vuong N, Petersen LR, et al. SARS-CoV-2 seroprevalence among healthcare, first response, and public safety personnel, Detroit metropolitan area, Michigan, USA, May-June 2020. Emerg Infect Dis. 2020;26:2863-2871. [PMID: 32956614] doi:10.3201/eid2612.203764 CrossrefMedlineGoogle Scholar11. Sims MD, Maine GN, Childers KL, et al; BLAST COVID-19 Study Group. COVID-19 seropositivity and asymptomatic rates in healthcare workers are associated with job function and masking. Clin Infect Dis. 2020. [PMID: 33150375] doi:10.1093/cid/ciaa1684 Google Scholar Comments 0 Comments Sign In to Submit A Comment Kurt Elward, MD, MPHSentara Medical Group22 March 2021 Very Useful and Timely I greatly value and respect the Update Alerts developed by Chou et al. They are extremely well done and rigorous in their analysis. The importance of well designed trials is even more evident. To have this objective report is invaluable as we attempt to focus on an effective, multifaceted approach against COVID-19 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, OregonDisclaimer: 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 AHRQ or HHS.Disclosures: Disclosures can be viewed at www.acponline.org/authors/icmje/ConflictOfInterestForms.do?msNum=L21-0116.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 9 March 2021. 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. McDonagh 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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