'Did you have flu last week?' A telephone survey to estimate a point prevalence of influenza in the Swedish population

Euro Surveill. 2005 Dec;10(12):241-4.


Sentinel surveillance usually underestimates the true burden of influenza in a population, as individuals must present to medical establishments to be included in the surveillance system. We carried out a telephone survey to estimate the national burden of influenza in the Swedish population for one week during the 2004/05 influenza season. Fixed-line telephone numbers were randomly sampled and households interviewed concerning influenza illness between 14-20 February 2005 (Week 7 of 2005). Questions regarding seasonal influenza vaccination status, symptoms and the impact of illness on daily life were also included. A self-defined influenza prevalence of 7.7% in week 7 of 2005 was estimated. On applying a case definition of 'cough and fever and muscle pain' for influenza like illness, the prevalence decreased to 3.6%. The survey provided insight into the burden of illness in the population further to that estimated through the sentinel surveillance system.

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Child
  • Child, Preschool
  • Cough / etiology
  • Cross-Sectional Studies
  • Data Collection
  • Fever / etiology
  • Humans
  • Infant
  • Infant, Newborn
  • Influenza, Human / complications
  • Influenza, Human / epidemiology*
  • Influenza, Human / physiopathology
  • Influenza, Human / prevention & control
  • Middle Aged
  • Muscles
  • Pain / etiology
  • Prevalence
  • Retrospective Studies
  • Severity of Illness Index
  • Sweden / epidemiology
  • Vaccination