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Médecine du travail du personnel hospitalier

A cluster randomized clinical trial comparing fit-tested and non-fit-tested N95 respirators to medical masks to prevent respiratory virus infection in health care workers

Auteur     Chandini Raina Macintyre
Auteur     Quanyi Wang
Auteur     Simon Cauchemez
Auteur     Holly Seale
Auteur     Dominic E Dwyer
Auteur     Peng Yang
Auteur     Weixian Shi
Auteur     Zhanhai Gao
Auteur     Xinghuo Pang
Auteur     Yi Zhang
Auteur     Xiaoli Wang
Auteur     Wei Duan
Auteur     Bayzidur Rahman
Auteur     Neil Ferguson
Résumé     Background  We compared the efficacy of medical masks, N95 respirators (fit tested and non fit tested), in health care workers (HCWs). Methods  A cluster randomized clinical trial (RCT) of 1441 HCWs in 15 Beijing hospitals was performed during the 2008/2009 winter. Participants wore masks or respirators during the entire work shift for 4 weeks. Outcomes included clinical respiratory illness (CRI), influenza-like illness (ILI), laboratory-confirmed respiratory virus infection and influenza. A convenience no-mask/respirator group of 481 health workers from nine hospitals was compared. Findings  The rates of CRI (3·9% versus 6·7%), ILI (0·3% versus 0·6%), laboratory-confirmed respiratory virus (1·4% versus 2·6%) and influenza (0·3% versus 1%) infection were consistently lower for the N95 group compared to medical masks. By intention-to-treat analysis, when P values were adjusted for clustering, non-fit-tested N95 respirators were significantly more protective than medical masks against CRI, but no other outcomes were significant. The rates of all outcomes were higher in the convenience no-mask group compared to the intervention arms. There was no significant difference in outcomes between the N95 arms with and without fit testing. Rates of fit test failure were low. In a post hoc analysis adjusted for potential confounders, N95 masks and hospital level were significant, but medical masks, vaccination, handwashing and high-risk procedures were not. Interpretation  Rates of infection in the medical mask group were double that in the N95 group. A benefit of respirators is suggested but would need to be confirmed by a larger trial, as this study may have been underpowered. The finding on fit testing is specific to the type of respirator used in the study and cannot be generalized to other respirators. Trial registration  Australian New Zealand Clinical Trials Registry (ANZCTR), ACTRN: ACTRN12609000257268 (
Publication     Influenza and Other Respiratory Viruses
Volume     5
Numéro     3
Pages     170-179
Date     May 2011

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