Comparison of Pandemic (H1N1) 2009 and Seasonal Influenza, Western Australia, 2009

摘要

We compared confi rmed pandemic (H1N1) 2009 in-. uenza and seasonal in. uenza diagnosed in Western Australia during the 2009 in. uenza season. From 3,178 eligible reports, 984 pandemic and 356 seasonal in. uen-za patients were selected; 871 (88.5%) and 288 (80.9%) were interviewed, respectively. Patients in both groups re-ported a median of 6 of 11 symptoms; the difference be-tween groups in the proportion reporting any given symp-tom was 1 underlying condition, and only diabetes was as-sociated with pandemic (H1N1) 2009 in. uenza (odds ratio [OR] 1.9, 95% confi dence interval [CI] 1.1–3.5). A total of 129 (14.8%) persons with pandemic (H1N1) 2009 and 36 (12.5%) persons with seasonal in. uenza were hospital-ized (p = 0.22). After controlling for age, we found that pa-tient hospitalization was associated with pandemic (H1N1) 2009 in. uenza (OR 1.5; 95% CI 1.1–2.1). Contempora-neous pandemic and seasonal in. uenza infections were substantially similar in terms of patients' symptoms, risk factors, and proportion hospitalized