title: Cluster randomised controlled trial to examine medical mask use as source control for people with respiratory illness.
abstract: Medical masks are commonly used by sick individuals with influenza-like illness (ILI) to prevent spread of infections to others, but clinical efficacy data are absent.
  
  
  
  Determine whether medical mask use by sick individuals with ILI protects well contacts from related respiratory infections.
  
  
  
  6 major hospitals in 2 districts of Beijing, China.
  
  
  
  Cluster randomised controlled trial.
  
  
  
  245 index cases with ILI.
  
  
  
  Index cases with ILI were randomly allocated to medical mask (n=123) and control arms (n=122). Since 43 index cases in the control arm also used a mask during the study period, an as-treated post hoc analysis was performed by comparing outcomes among household members of index cases who used a mask (mask group) with household members of index cases who did not use a mask (no-mask group).
  
  
  
  Primary outcomes measured in household members were clinical respiratory illness, ILI and laboratory-confirmed viral respiratory infection.
  
  
  
  In an intention-to-treat analysis, rates of clinical respiratory illness (relative risk (RR) 0.61, 95% CI 0.18 to 2.13), ILI (RR 0.32, 95% CI 0.03 to 3.13) and laboratory-confirmed viral infections (RR 0.97, 95% CI 0.06 to 15.54) were consistently lower in the mask arm compared with control, although not statistically significant. A post hoc comparison between the mask versus no-mask groups showed a protective effect against clinical respiratory illness, but not against ILI and laboratory-confirmed viral respiratory infections.
  
  
  
  The study indicates a potential benefit of medical masks for source control, but is limited by small sample size and low secondary attack rates. Larger trials are needed to confirm efficacy of medical masks as source control.
  
  
  
  ACTRN12613000852752; Results.
authors.affiliation: School of Public Health and Community Medicine UNSW Medicine University of New South Wales, Sydney, New South Wales, Australia.|College of Public Service & Community Solutions, Arizona State University, Phoenix, Arizona, USA.
authors.forename: Chandini Raina
authors.initials: CR
authors.lastname: MacIntyre
authors.affiliation: The Beijing Centre for Disease Prevention and Control Beijing China, XiCheng district CDC Beijing China, Dongcheng district CDC Beijing, Beijing, China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: School of Public Health and Community Medicine UNSW Medicine University of New South Wales, Sydney, New South Wales, Australia.|College of Public Service & Community Solutions, Arizona State University, Phoenix, Arizona, USA.
authors.forename: Abrar Ahmad
authors.initials: AA
authors.lastname: Chughtai
authors.affiliation: School of Public Health and Community Medicine UNSW Medicine University of New South Wales, Sydney, New South Wales, Australia.|College of Public Service & Community Solutions, Arizona State University, Phoenix, Arizona, USA.
authors.forename: Holly
authors.initials: H
authors.lastname: Seale
authors.affiliation: The Beijing Centre for Disease Prevention and Control Beijing China, XiCheng district CDC Beijing China, Dongcheng district CDC Beijing, Beijing, China.
authors.forename: Daitao
authors.initials: D
authors.lastname: Zhang
authors.affiliation: The Beijing Centre for Disease Prevention and Control Beijing China, XiCheng district CDC Beijing China, Dongcheng district CDC Beijing, Beijing, China.
authors.forename: Yanhui
authors.initials: Y
authors.lastname: Chu
authors.affiliation: The Beijing Centre for Disease Prevention and Control Beijing China, XiCheng district CDC Beijing China, Dongcheng district CDC Beijing, Beijing, China.
authors.forename: Haiyan
authors.initials: H
authors.lastname: Zhang
authors.affiliation: School of Public Health and Community Medicine UNSW Medicine University of New South Wales, Sydney, New South Wales, Australia.|College of Public Service & Community Solutions, Arizona State University, Phoenix, Arizona, USA.
authors.forename: Bayzidur
authors.initials: B
authors.lastname: Rahman
authors.affiliation: The Beijing Centre for Disease Prevention and Control Beijing China, XiCheng district CDC Beijing China, Dongcheng district CDC Beijing, Beijing, China.
authors.forename: Quanyi
authors.initials: Q
authors.lastname: Wang
mesh_terms: D000328:Adult; D002681:China / Q000453:epidemiology; D016000:Cluster Analysis; D005191:Family Characteristics; D005260:Female; D006801:Humans; D017053:Infection Control / Q000295:instrumentation / Q000379:methods*; D007251:Influenza, Human / Q000517:prevention & control*; D008297:Male; D008397:Masks; D017063:Outcome Assessment, Health Care; D016016:Proportional Hazards Models; D012134:Respiratory Protective Devices / Q000706:statistics & numerical data*; D012141:Respiratory Tract Infections / Q000517:prevention & control*
keywords: Influenza; Mask