Pandemic (H1N1) 2009 influenza in the UK: Clinical and epidemiological findings from the first few hundred (FF100) cases

Academic Article


  • The UK was one of few European countries to document a substantial wave of pandemic (H1N1) 2009 influenza in summer 2009. The First Few Hundred (FF100) project ran from April-June 2009 gathering information on early laboratory-confirmed cases across the UK. In total, 392 confirmed cases were followed up. Children were predominantly affected (median age 15 years, IQR 10-27). Symptoms were mild and similar to seasonal influenza, with the exception of diarrhoea, which was reported by 27%. Eleven per cent of all cases had an underlying medical condition, similar to the general population. The majority (92%) were treated with antiviral drugs with 12% reporting adverse effects, mainly nausea and other gastrointestinal complaints. Duration of illness was significantly shorter when antivirals were given within 48 h of onset (median 5 vs. 9 days, P=001). No patients died, although 14 were hospitalized, of whom three required mechanical ventilation. The FF100 identified key clinical and epidemiological characteristics of infection with this novel virus in near real-time. Copyright © 2010 Cambridge University Press.
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    Digital Object Identifier (doi)

    Author List

  • McLean E; Pebody RG; Campbell C; Chamberland M; Hawkins C; Nguyen-Van-Tam JS; Oliver I; Smith GE; Ihekweazu C; Bracebridge S
  • Start Page

  • 1531
  • End Page

  • 1541
  • Volume

  • 138
  • Issue

  • 11