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Relative Efficacy of Masks and Respirators as Source Control for Viral Aerosol Shedding from People Infected with SARS-CoV-2: A Human Controlled Trial
18 Pages Posted: 15 Nov 2023
More...Abstract
Background: Tight-fitting masks and respirators, in manikin studies, improved aerosol source control compared to loose-fitting masks. Whether this translates to humans is not known.
Methods: We compared efficacy of masks (cloth and surgical) and respirators (KN95 and N95) as source control for SARS-CoV-2 viral load in exhaled breath of volunteers with COVID-19. Volunteers provided paired unmasked and masked breath samples allowing computation of source-control factors.
Findings: All masks and respirators significantly reduced exhaled viral load, without fit tests or training. A duckbill N95 reduced exhaled viral load by 98% (95% CI: 97% to 99%), and significantly outperformed a KN95 (p<0·001) as well as cloth and surgical masks. Cloth masks outperformed a surgical mask (p=0·012) and the tested KN95 (p=0·028).
Interpretation: These results suggest that N95 respirators could be the standard of care in nursing homes and healthcare settings when respiratory viral infections are prevalent in the community and healthcare-associated transmission risk is elevated.
Funding: This work was supported by the Prometheus-UMD, sponsored by the Defense Advanced Research Projects Agency (DARPA) BTO under the auspices of Col. Matthew Hepburn through agreement N66001-18-2-4015, the National Institute of Allergy and Infectious Diseases Centers of Excellence for Influenza Research and Surveillance (CEIRS) Contract Number HHSN272201400008C, and the Centers for Disease Control and Prevention Contract Number 200-2020-09528; by a grant from the Bill & Melinda Gates Foundation; and by a generous gift from The Flu Lab (https://theflulab.org).
Declaration of Interest: B.J.C. consults for AstraZeneca, Fosun Pharma, GlaxoSmithKline, Haleon, Moderna, Novavax, Pfizer, Roche, and Sanofi Pasteur. D.K.M. consults for A.I.R LLC. The authors declare no other competing interests.
Ethical Approval: This study was conducted at the University of Maryland, College Park (UMD). It was approved by the University of Maryland Institutional Review Board and the Human Research Protection Office of the Department of the Navy. Informed consent was obtained from all study participants.
Keywords: Source control, SARS-CoV-2, surgical masks, respirators, exhaled breath aerosols
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