Is the use of N95 respirators or medical masks more effective in preventing influenza infection among outpatient health care personnel in close contact with patients with suspected respiratory illness?
In this pragmatic, cluster randomized clinical trial involving 2862 health care personnel, there was no significant difference in the incidence of laboratory-confirmed influenza among health care personnel with the use of N95 respirators (8.2%) vs medical masks (7.2%).
As worn by health care personnel in this trial, use of N95 respirators, compared with medical masks, in the outpatient setting resulted in no significant difference in the rates of laboratory-confirmed influenza.
Clinical studies have been inconclusive about the effectiveness of N95 respirators and medical masks in preventing health care personnel (HCP) from acquiring workplace viral respiratory infections.
To compare the effect of N95 respirators vs medical masks for prevention of influenza and other viral respiratory infections among HCP.
Design, Setting, and Participants
A cluster randomized pragmatic effectiveness study conducted at 137 outpatient study sites at 7 US medical centers between September 2011 and May 2015, with final follow-up in June 2016. Each year for 4 years, during the 12-week period of peak viral respiratory illness, pairs of outpatient sites (clusters) within each center were matched and randomly assigned to the N95 respirator or medical mask groups.
Overall, 1993 participants in 189 clusters were randomly assigned to wear N95 respirators (2512 HCP-seasons of observation) and 2058 in 191 clusters were randomly assigned to wear medical masks (2668 HCP-seasons) when near patients with respiratory illness.
Main Outcomes and Measures
The primary outcome was the incidence of laboratory-confirmed influenza. Secondary outcomes included incidence of acute respiratory illness, laboratory-detected respiratory infections, laboratory-confirmed respiratory illness, and influenzalike illness. Adherence to interventions was assessed.
Among 2862 randomized participants (mean [SD] age, 43 [11.5] years; 2369 [82.8%]) women), 2371 completed the study and accounted for 5180 HCP-seasons. There were 207 laboratory-confirmed influenza infection events (8.2% of HCP-seasons) in the N95 respirator group and 193 (7.2% of HCP-seasons) in the medical mask group (difference, 1.0%, [95% CI, −0.5% to 2.5%]; P = .18) (adjusted odds ratio [OR], 1.18 [95% CI, 0.95-1.45]). There were 1556 acute respiratory illness events in the respirator group vs 1711 in the mask group (difference, −21.9 per 1000 HCP-seasons [95% CI, −48.2 to 4.4]; P = .10); 679 laboratory-detected respiratory infections in the respirator group vs 745 in the mask group (difference, −8.9 per 1000 HCP-seasons, [95% CI, −33.3 to 15.4]; P = .47); 371 laboratory-confirmed respiratory illness events in the respirator group vs 417 in the mask group (difference, −8.6 per 1000 HCP-seasons [95% CI, −28.2 to 10.9]; P = .39); and 128 influenzalike illness events in the respirator group vs 166 in the mask group (difference, −11.3 per 1000 HCP-seasons [95% CI, −23.8 to 1.3]; P = .08). In the respirator group, 89.4% of participants reported “always” or “sometimes” wearing their assigned devices vs 90.2% in the mask group.
Conclusions and Relevance
Among outpatient health care personnel, N95 respirators vs medical masks as worn by participants in this trial resulted in no significant difference in the incidence of laboratory-confirmed influenza.
ClinicalTrials.gov Identifier: NCT01249625
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CME Disclosure Statement: Unless noted, all individuals in control of content reported no relevant financial relationships. If applicable, all relevant financial relationships have been mitigated.
Corresponding Author: Lewis J. Radonovich Jr, MD, National Personal Protective Technology Laboratory, Centers for Disease Control and Prevention, 626 Cochrans Mill Rd, B141, R108, Pittsburgh, PA 15236 (firstname.lastname@example.org).
Accepted for Publication: July 25, 2019.
Author Contributions: Drs Perl and Radonovich had full access to all of the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis.
Concept and design: Radonovich, Simberkoff, Cummings, Gaydos, Gorse, Reich, Perl.
Acquisition, analysis, or interpretation of data: All authors.
Drafting of the manuscript: Radonovich, Simberkoff, Cummings, Gaydos, Nyquist, Reich, Perl.
Critical revision of the manuscript for important intellectual content: Radonovich, Bessesen, Brown, Cummings, Gaydos, Los, Krosche, Gibert, Gorse, Nyquist, Reich, Rodriguez-Barradas, Price, Perl.
Statistical analysis: Brown, Cummings, Reich.
Obtained funding: Cummings, Perl.
Administrative, technical, or material support: Radonovich, Simberkoff, Bessesen, Cummings, Gaydos, Los, Krosche, Gorse, Nyquist, Rodriguez-Barradas, Price, Perl.
Supervision: Radonovich, Simberkoff, Cummings, Los, Nyquist, Reich, Price, Perl.
Other - execution of study design; data management and monitoring: Los.
Other - Site principal investigator for conduct of study and also contributed ongoing input on conduct and analysis of study: Gibert.
Other - laboratory testing support: Gaydos.
Other - recruiting patients: Price.
Conflict of Interest Disclosures: Dr Bessesen reported receiving grants from the Department of Veterans Affairs during the conduct of the study. Dr Brown reported receiving grants from the US Department of Veterans Affairs during the conduct of the study. Dr Cummings reported receiving grants from the Centers for Disease Control and Prevention, the National Institutes of Health, and MedImmune outside the submitted work and the Biomedical Advanced Research and Development Authority during the conduct of the study. Ms Los reported receiving grants from Centers for Disease Control and Prevention, the Veterans Health Administration, and the Biodefense Advanced Research and Development Agency during the conduct of the study. Dr Gibert reported receiving financial support for the conduct of the study, including research personnel, from the Veterans Health Administration during the conduct of the study. Dr Gorse reported receiving grants from the US Department of Veterans Affairs during the conduct of the study. Dr Nyquist reported receiving grants from the Centers for Disease Control and Prevention/Division of Healthcare Quality Promotion, the National Institute for Occupational Safety and Health, and the Veterans Health Administration during the conduct of the study; personal fees and nonfinancial support from Sequirus outside the submitted work; and serving on a policy making committee regarding infectious disease for the American Academy of Pediatrics Committee on Infectious Diseases. Dr Reich reported receiving grants from Veterans Health Administration during the conduct of the study. Dr Rodriguez-Barradas reported receiving grants from Veterans Affairs Central Office during the conduct of the study. Dr Perl reported receiving grants from the Centers for Disease Control and Prevention and Biomedical Advanced Research and Development Authority during the conduct of the study and grants from Medimmune outside the submitted work. No other disclosures were reported.
Funding/Support: This trial was funded by the US Centers for Disease Control and Prevention, Veterans Health Administration, and the Biodefense Advanced Research and Development Agency.
Role of the Funder/Sponsor: The sponsors were not involved in data collection, analysis, or interpretation; writing of the manuscript; or the decision to submit the manuscript. The sponsors reviewed and made technical comments about the study protocol prior to enrollment and the final manuscript prior to submission for publication.
Group Information: For the ResPECT Team (Contributors): The Johns Hopkins University and Health System (Baltimore, MD): Trish M. Perl, MD, MSc; Justin Getka, BA; Tina Hoang, MS; Rose Kajih, PharmD; Amanda Krosche, BS; Meghan Kubala, MS, MD: Jenna Los, MLA; Liandra Presser, MD; Kathleen Pulice, MS; Margaret Spach, DDS. VA New York Harbor Healthcare System (New York, NY): Michael S. Simberkoff, MD; Cynthia Akagbosu, BA, MA; Madeline Dansky, BA; Benedict J. Frederick, BA; Marilyn Last, RN; Scott Laverie, RN; Courtney Pike, BA; Shefali Rikhi, BS; Nicole Spector, RN; Christine A. Reel-Brander, RN. Denver Health & Hospital Authority (Denver, CO): Connie Price, MD; Katie Gorman, BS; Amy Irwin, DNP, RN; Sean O’Malley; Kevin Silva, BS. UT Southwestern Medical Center (Dallas, TX) Trish M. Perl, MD, MSc; Deepa Raj, MPH; VA Eastern Colorado Healthcare System (Aurora, CO): Mary Bessesen, MD; Jill C. Adams BSN, BA; Shannon Kingery, BS; Stefanie Tuder, BS; Erron Fritchman-Palmer, MPH. Children’s Hospital Colorado (Denver, CO): Ann-Christine Nyquist, MD, MSPH; Megan Gorski, BA. VA Washington DC Medical Center (Washington, DC): Cynthia Gibert, MD, MSc; Laura Chopko, BA; Kathy Haines, MSW, MPH; Caitlin Langhorne, MPH; Dana Silver, BA; Courtney Southard, MPH. VA Michael C. DeBakey Medical Center (Houston, TX): Maria C. Rodriguez-Barradas MD; Barbara Kertz, MS; Mahwish Mushtaq, MD, MPH; Blanca Vargas, MD. Centers for Disease Control and Prevention, National Institute for Occupational Safety & Health (Pittsburgh, PA): Edward Fisher, MS; Ronald Shaffer, PhD; Lewis J. Radonovich, MD. Veteran’s Health Administration Office of Public Health (Gainesville, FL): Aaron Eagan, MPH, RN; Lewis J. Radonovich, MD. HandyMetrics Corporation (Toronto, Ontario, Canada): Melanie Lipka, BS; Michael Tsang, PhD. Laboratory Core at Johns Hopkins University (Baltimore, MD): Charlotte Gaydos, DrPH, Jeffrey Holden, MA; Alexandra Valsamakis, MD, PhD. Laboratory Core at VA St Louis Healthcare System and St Louis University School of Medicine (St Louis, MO): Geoffrey J. Gorse, MD; Michelle Mitchell, BS; Gira B. Patel, MS; Yinyi Yu, BS. REDCap Core at Johns Hopkins University (Baltimore, MD): Andre Hackman, BA, Michael Sherman, BS. Statistical and Epidemiologic Core (University of Florida, Gainesville): Brooke A. Borgert MS., Derek A.T. Cummings, PhD, MPH, MSc.; Susan Rattigan (University of Massachusetts, Amherst): Alexandria C. Brown, PhD; Nicholas G. Reich, PhD (Johns Hopkins University, Baltimore, MD); Justin Lessler, PhD, MHS, MS.
Disclaimer: The findings and conclusions in this article are the authors’ own and do not necessarily represent the views of the National Institute for Occupational Safety and Health, the Centers for Disease Control and Prevention, the Department of Veterans Affairs, or other affiliates. Mention of product names does not imply endorsement. All information and materials in this article are original.
Data Sharing Statement: See Supplement 4.
Additional Contributions: We thank the members of the data and safety monitoring board, Daniel Morgan, MD (University of Maryland, Baltimore), Elizabeth Colantuoni, PhD (Johns Hopkins Bloomberg School of Public Health, Baltimore), and Tia Powell, MD (Albert Einstein College of Medicine, Bronx). We also thank David Weissman, MD (National Institute for Occupational Safety and Health) and Michael Hodgson, MD (Occupational Safety and Health Administration). None of our consults were financially compensated for their expertise, support, and guidance throughout the study. We are immensely grateful to the study personnel and coordinators, the supporting clinical staff, and, most importantly, the participants.
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