The comaprison of clinical characteristics and courses of pediatric patients hospitalized with pandemic influenza A (H1N1) and seasonal influenza in Korea from 2009-2011

Introduction: Pandemic influenza viruses have caused significant morbidity and mortality. Pandemic influenza A (H1N1) was detected in April 2009 and caused worldwide outbreak. Objectives: We wanted to investigate the differences in clinical characteristics and courses between pandemic and seasonal influenzas. Methods: We reviewed the medical records of pediatric patients, (≤18 years) with influenza hospitalized to Gachon University Gil Medical Center in Korea from the 1 April 2009 to the 31 August 2011. Results: Two hundred twenty-six patients with pandemic influenza and 118 patients with seasonal influenza were included. Age, sex, and proportion of underlying diseases were similar between the two groups. Hypoxemia, shortness of breath, and tachypnea were more common in pandemic influenza.( P <0.05) Oxygen supplementation and radiologically confirmed pneumonia were more common in pandemic influenza.( P <0.005) However, there were no significant differences in the mean duration of hospitalization, proportion of patients admitted to the intensive care unit, need for mechanical ventilation, and death. Conclusion: Pandemic influenza caused more frequently lower respiratory tract infection and pneumonia. However, the courses of pandemic influenza were not different from those of seasonal influenza; probably, due to the effects of several factors, including antiviral therapy.