Background

This surveillance report summarizes the search and update for the rapid review and living update on the effectiveness and comparative effectiveness of various types of facemasks in the community and in healthcare workers for prevention of infection with SARS-CoV-2 (the cause of coronavirus disease 2019 [COVID-19]) and the effectiveness and safety of mask reuse.

Given this rapidly emerging field and the urgent need for answers, the AHRQ Evidence-based Practice Center program is conducting regular surveillance and updating this report on a regular basis. When studies are identified but do not change the conclusions, findings will be summarized in a surveillance report. When studies lead to a change in conclusions, the report will be updated.

This surveillance report documents the yield from an update search based on Version 2 (search end date July 2, 2020).

Table 1

Version and update history.

Surveillance

Searches were updated from June 2 to July 2, 2020. The same search strategies and inclusion criteria were used as the original review, except that we dropped the search on the medRxiv preprint server and excluded non-peer-reviewed studies. The surveillance search identified 321 citations and identified one additional study for this update (Appendix B). See the review protocol for further details https://effectivehealthcare.ahrq.gov/products/masks-covid/protocol.

Table 2

Summary of conclusions and surveillance assessment.

Evidence Summary

No study in the original review evaluated effects of mask use in the community and risk of SARS-CoV-2 infection. One new observational study¹ on mask use and risk of SARS-CoV-2 infection in community settings was identified for this surveillance report.

The new study was a retrospective cohort study of 124 households with an index SARS-CoV-2 case and 355 uninfected household contacts.¹ Households in which masks were used by at least one family member (including the index case) prior to the development of symptoms by the index case were associated with decreased risk of incident infections, after adjusting for other hygiene and infection control practices, physical distance to index case, environmental factors, and presence of diarrhea in the index case (adjusted odds ratio 0.21, 95% confidence interval 0.06 to 0.79). There was no association between mask use after illness onset in the index case and risk of SARS-CoV-2 infections in family members. Masks included N95 respirators, surgical masks, or cloth face coverings, and the study did not conduct analyses by specific mask type. The study was susceptible to recall bias; in addition, the analysis used households (rather than exposed individuals) as the unit of analysis and did not analyze mask use by the index case (“source control”) separately from mask use by household contacts. The applicability of findings to wearing of masks in public is also uncertain. Therefore, the strength of evidence on masks in community settings for prevention of SARS-CoV-2 infection is insufficient.

No new study evaluated the effects of mask use and risk of SARS-CoV-2 infection in healthcare settings or effects of mask use and risk of SARS-CoV-1 infection, MERS-CoV infection (the cause of Middle East Respiratory Syndrome), or influenza/influenzalike illness.

References

1.

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 May;5(5)doi: 10.1136/bmjgh-2020-002794. PMID: 32467353. [PMC free article: PMC7264640] [PubMed: 32467353] [CrossRef]

Acknowledgements

The authors thank the Timothy Wilt, M.D., M.P.H., who served as associate editor for this review, and Christine Chang, M.D., M.P.H., associate director of the Evidence-based Practice Center Program.

Afterword

Recognized for excellence in conducting comprehensive systematic reviews, the Agency for Healthcare Research and Quality (AHRQ) Evidence-based Practice Center (EPC) program is developing a range of rapid evidence products to assist end-users in making specific decisions in a limited timeframe.

The AHRQ EPC Program recognizes that people are struggling with urgent questions on how to control the COVID-19 pandemic. To shorten timelines, reviewers make strategic choices about which review processes to abridge. However, the adaptations made for expediency may limit the certainty and generalizability of the findings from the review, particularly in areas with a large literature base. Transparent reporting of the methods used and the resulting limitations of the evidence synthesis are extremely important.

Given the rapidly evolving field, the AHRQ EPC Program will update these reviews on a regular basis to keep the medical community and public up to date as more studies are published through the summer of 2020. If you have comments or have unpublished data to share related to this report, they may be sent by mail to the Task Order Officer named below at: Agency for Healthcare Research and Quality, 5600 Fishers Lane, Rockville, MD 20857, or by email to vog.shh.qrha@cpe and will be considered in the next version of the report.

• Gopal Khanna, M.B.A
  Director
  Agency for Healthcare Research and Quality
• Stephanie Chang, M.D., M.P.H.
  Director
  Evidence-based Practice Center Program
  Center for Evidence and Practice Improvement
  Agency for Healthcare Research and Quality
• Christine S. Chang, M.D., M.P.H
  Associate Director
  Evidence-based Practice Center Program
  Center for Evidence and Practice Improvement
  Agency for Healthcare Research and Quality
• Arlene S. Bierman, M.D., M.S.
  Director
  Center for Evidence and Practice Improvement
  Agency for Healthcare Research and Quality

Appendix A. Evidence Tables

See associated Excel^® files:

• Table B-1. Randomized controlled trials of mask use (MS Excel, 37K)

• Table B-2. Observational studies of mask use in community settings: Updated (MS Excel, 13K)

• Table B-3. Observational studies of mask use in healthcare settings (MS Excel, 20K)

Appendix B. Literature Flow Diagram

*One new study added

Suggested citation:

Chou R, Dana T, Jungbauer R, Weeks C, McDonagh M. Masks for Prevention of COVID-19 in Community and Healthcare Settings. Surveillance Report. (Prepared by the Pacific Northwest Evidence-based Practice Center under Contract No. 290-2015-00009-I). AHRQ Publication No. 20-EHC020. Rockville, MD: Agency for Healthcare Research and Quality. July 2020. Posted final reports are located on the Effective Health Care Program search page. DOI: https://doi.org/10.23970/AHRQEPCCOVIDMASKSSURVEILLANCEJULY2020.

Disclaimers: This report is based on research conducted by the Pacific Northwest Evidence-based Practice Center under contract to the Agency for Healthcare Research and Quality (AHRQ), Rockville, MD (Contract No. 290-2015-00009-I). The findings and conclusions in this document are those of the authors, who are responsible for its contents; the findings and conclusions do not necessarily represent the views of AHRQ. Therefore, no statement in this report should be construed as an official position of AHRQ or of the U.S. Department of Health and Human Services.

None of the investigators have any affiliations or financial involvement that conflicts with the material presented in this report.

The information in this report is intended to help health care decision makers—patients and clinicians, health system leaders, and policymakers, among others—make well-informed decisions and thereby improve the quality of health care services. This report is not intended to be a substitute for the application of clinical judgment. Anyone who makes decisions concerning the provision of clinical care should consider this report in the same way as any medical reference and in conjunction with all other pertinent information, i.e., in the context of available resources and circumstances presented by individual patients.

This report is made available to the public under the terms of a licensing agreement between the author and the Agency for Healthcare Research and Quality. This report may be used and reprinted without permission except those copyrighted materials that are clearly noted in the report. Further reproduction of those copyrighted materials is prohibited without the express permission of copyright holders.

AHRQ or U.S. Department of Health and Human Services endorsement of any derivative products that may be developed from this report, such as clinical practice guidelines, other quality enhancement tools, or reimbursement or coverage policies, may not be stated or implied.

AHRQ appreciates appropriate acknowledgment and citation of its work. Suggested language for acknowledgment: This work was based on an evidence report, Masks for Prevention of COVID-19 in Community and Healthcare Settings, Surveillance Report, by the Evidence-based Practice Center Program at the Agency for Healthcare Research and Quality (AHRQ).