Epidemiology and Infection

Original Papers


Impact of medical and behavioural factors on influenza-like illness, healthcare-seeking, and antiviral treatment during the 2009 H1N1 pandemic: USA, 2009–2010

M. BIGGERSTAFFa1 c1, M. A. JHUNGa1, C. REEDa1, S. GARGa1a2, L. BALLUZa3, A. M. FRYa1 and L. FINELLIa1

a1 Epidemiology and Prevention Branch, Influenza Division, National Center for Immunization and Respiratory Disease, Centers for Disease Control and Prevention, Atlanta, GA, USA

a2 Epidemic Intelligence Service, Centers for Disease Control and Prevention, Atlanta, GA, USA

a3 Division of Behavioral Surveillance, Office of Surveillance, Epidemiology, and Laboratory Services, Centers for Disease Control and Prevention, Atlanta, GA, USA


We analysed a cross-sectional telephone survey of U.S. adults to assess the impact of selected characteristics on healthcare-seeking behaviours and treatment practices of people with influenza-like illness (ILI) from September 2009 to March 2010. Of 216 431 respondents, 8·1% reported ILI. After adjusting for selected characteristics, respondents aged 18–64 years with the following factors were more likely to report ILI: a diagnosis of asthma [adjusted odds ratio (aOR) 1·88, 95% CI 1·67–2·13] or heart disease (aOR 1·41, 95% CI 1·17–1·70), being disabled (aOR 1·75, 95% CI 1·57–1·96), and reporting financial barriers to healthcare access (aOR 1·63, 95% CI 1·45–1·82). Similar associations were seen in respondents aged ≥65 years. Forty percent of respondents with ILI sought healthcare, and 14% who sought healthcare reported receiving influenza antiviral treatment. Treatment was not more frequent in patients with high-risk conditions, except those aged 18–64 years with heart disease (aOR 1·90, 95% CI 1·03–3·51). Of patients at high risk for influenza complications, self-reported ILI was greater but receipt of antiviral treatment was not, despite guidelines recommending their use in this population.

(Received October 03 2012)

(Revised January 22 2013)

(Accepted February 27 2013)

(Online publication March 25 2013)

Key words

  • Healthcare-seeking behaviour;
  • influenza;
  • influenza A(H1N1)pdm09;
  • influenza antiviral treatment