Travel and Age of Influenza A (H1N1) 2009 Virus Infection


  • Hiroshi Nishiura MD, PhD

    Corresponding author
    1. PRESTO, Japan Science and Technology Agency, Saitama, Japan
    2. Theoretical Epidemiology, University of Utrecht,
      Utrecht, The Netherlands
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Hiroshi Nishiura, MD, PhD, University of Utrecht, Yalelaan 7, 3584 CL Utrecht, The Netherlands. E-mail:


Age distribution of 4,986 cases of influenza A (H1N1) 2009 in Japan was analyzed. Cases with a travel history within 10 days preceding the illness onset were significantly older than indigenous cases (p < 0.01) reflecting age-specific travel patterns. Border controls should account for the high frequency of infection among adults.