Hospitalisation rates for seasonal influenza are highest among young children and people aged over 65 years. Calculation of laboratory-confirmed infection rates is difficult because influenza testing is not consistently performed. Using diagnostic codes to identify hospitalisations for acute respiratory illness provides one measure of the relative burden of pandemic (H1N1) 2009 (pH1N1) virus infection compared with influenza virus infections in previous influenza seasons.
Medical Journal of Australia Vol. 191, Issue 10, p. 573-574