Recurring influenza virus infections and implications in terms of epidemic recurrences and pandemic risk. FRESH-PEF5081-en Fabrice CARRAT Recurring influenza virus infections and implications in terms of epidemic recurrences and pandemic risk. Flurec FRESH-PEF5081-en 5081 FRESH-PEF5081 Fabrice CARRAT Xavier DE LAMBALLERIE ASSISTANCE PUBLIQUE HOPITAUX DE PARIS (AP-HP) Epidemiology France Portal (PEF) AGENCE NATIONALE DE LA RECHERCHE (ANR) INSTITUT NATIONAL DE LA SANTE ET DE LA RECHERCHE MEDICALE (INSERM) null Fabrice;CARRAT Xavier;DE LAMBALLERIE Cross-protective immunity A/H1N1 virus seasonal and pandemic A/H3N2 virus influenza infection risk evolution population Infectious disease medicine Socio-demographic and economic determinants To explore cross-protective immunity involving different A/H1N1 viruses (seasonal and pandemic) and the seasonal A/H3N2 virus through data gathered from this study. This study also aims to identify the epidemiological, immunological and virological factors that determine the risk of recurring influenza infections as well as characterise the population's herd immunity and its evolution. null France Individuals General population Male Female Young Adult (19 to 24 years) Adult (25 to 44 years) Middle Aged (45 to 64 years) Aged (65 to 79 years) The "influenza" group comprises of patients enrolled after general medical consultation for influenza-like illness during seasonal epidemic. The "non-influenza" group comprises of patients enrolled after general medical consultation during seasonal epidemic for a reason other than influenza, yet that was acute in nature e.g. infectious diarrhoea, minor trauma. Clinical data Biological data Health event/morbidity Health event/mortality Health care consumption and services Other Through independent healthcare practitioners [500-1000[ individuals Other Observational Study Observational Study Case-control study 534 Completed study Restricted access Clinical data and biological results of serological tests will be communicated upon presentation of ancillary project protocol. However biological samples will not be accessible. Access on specific project only