Facemasks and Hand Hygiene to Prevent Influenza Transmission in Households

Background: Few data are available about the effectiveness of nonpharmaceutical interventions for preventing influenza virus transmission. Objective: To investigate whether hand hygiene and use of face-masks prevents household transmission of influenza. Design: Cluster randomized, controlled trial. Randomization was computer generated; allocation was concealed from treating physi-cians and clinics and implemented by study nurses at the time of the initial household visit. Participants and personnel administering the interventions were not blinded to group assignment. (Clinical-Trials.gov registration number: NCT00425893) Setting: Households in Hong Kong. Patients: 407 people presenting to outpatient clinics with influenza-like illness who were positive for influenza A or B virus by rapid testing (index patients) and 794 household members (contacts) i