Clinical Trial to Assess the Influenza Vaccination (FLUVAC 02)

Inclusion Criteria: * Age ≥ 18 year * Affiliated with social security health insurance * Written informed consent * Patients hospitalized for 24 hours and presenting an influenza-like illness in the last 7 days before the hospitalization Exclusion Criteria: * Against indication for influenza vaccination(Hypersensitivity to the active substances, to any of the excipients and to trace eg eggs, including ovalbumin, chicken protein) * Patients institutionalized without regular community interaction * Patient already hospitalized for respiratory infection during the 2012-2013 influenza season * Flu already virologically documented in the current influenza season 2012-2013 (RT-PCR, multiple RT-PCR and / or culture.)