Demographic characteristics of 1520 UK patients hospitalised with pandemic H1N1 infection during the 2009/10 pandemic (The FLU-CIN Cohort) compared with source population and pre-pandemic hospital data on acute respiratory infection admissions.

Data are numbers (%), unless otherwise indicated.†Census 2001 Data for comparison of sex (KS01 tables) were obtained from the Office for National Statistics (ONS) (www.statistics.gov.uk). ‡Demographic data on age distribution based on 2009 mid-year population estimates, ONS.‡‡Ethnicity data from ONS (Census 2001 data, 2001 data from the General Register Office for Scotland and Northern Ireland Statistics and Research Agency). *Hospital Episodes Statistics (HES) data: primary discharge codes relating to possible influenza admissions (J06, J10, J11, J13–22) were considered for the pre-pandemic influenza active period Nov 2008-Mar 2009.