Meta Analysis Comparative Study
- Jessica J Bartoszko, Mohammed Abdul Malik Farooqi, Waleed Alhazzani, and Mark Loeb.
- Department of Health Research Methods, Evidence and Impact, McMaster University, Hamilton, ON, Canada.
- Influenza Other Respi Viruses. 2020 Jul 1; 14 (4): 365-373.
BackgroundRespiratory protective devices are critical in protecting against infection in healthcare workers at high risk of novel 2019 coronavirus disease (COVID-19); however, recommendations are conflicting and epidemiological data on their relative effectiveness against COVID-19 are limited.PurposeTo compare medical masks to N95 respirators in preventing laboratory-confirmed viral infection and respiratory illness including coronavirus specifically in healthcare workers.Data SourcesMEDLINE, Embase, and CENTRAL from January 1, 2014, to March 9, 2020. Update of published search conducted from January 1, 1990, to December 9, 2014.Study SelectionRandomized controlled trials (RCTs) comparing the protective effect of medical masks to N95 respirators in healthcare workers.Data ExtractionReviewer pair independently screened, extracted data, and assessed risk of bias and the certainty of the evidence.Data SynthesisFour RCTs were meta-analyzed adjusting for clustering. Compared with N95 respirators; the use of medical masks did not increase laboratory-confirmed viral (including coronaviruses) respiratory infection (OR 1.06; 95% CI 0.90-1.25; I2 = 0%; low certainty in the evidence) or clinical respiratory illness (OR 1.49; 95% CI: 0.98-2.28; I2 = 78%; very low certainty in the evidence). Only one trial evaluated coronaviruses separately and found no difference between the two groups (P = .49).LimitationsIndirectness and imprecision of available evidence.ConclusionsLow certainty evidence suggests that medical masks and N95 respirators offer similar protection against viral respiratory infection including coronavirus in healthcare workers during non-aerosol-generating care. Preservation of N95 respirators for high-risk, aerosol-generating procedures in this pandemic should be considered when in short supply.© 2020 The Authors. Influenza and Other Respiratory Viruses Published by John Wiley & Sons Ltd.
This article appears in the collections: Does face mask use reduce COVID transmission? and Anaesthesiology, Personal Protective Equipment (PPE) and COVID.
Note this is a systemic review of a small number of RCTs published very early in the COVID-19 pandemic, and notably only one of the four RCTs included coronarvirus, Loeb (2009), the others mainly focusing on influenza [MacIntyre (2011), MacIntyre (2013), Radonovich (2019)]. Obviously none of the studies specifically looked at SARS-CoV-2.
Subsequent N95/P2 mask studies since this have shown significant benefit of high-quality masks in reducing COVID-19 transmission.
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