Face Masks for Preventing Influenza Transmission

Inclusion Criteria: Patient seeking medical advice for: * For symptoms less than 48 hours, combining fever\> = 37.8 ° C and a cough, * during the period of a seasonal influenza epidemic (as defined by the Sentinel network) * Older than 5 years * And living in a household size between 3 to 8.. * The patient is the first case in the household (index patient). The patient has a positive rapid influenza A test. * Informed consent. * Affiliation to the social security. Exclusion Criteria: * When concomitant influenza cases are known in other householders * When the patient is suffering from asthma or COPD (ongoing treatment): * Hospitalization. * Treatment by a neuraminidase inhibitor.