Clinical characteristics of children with 2009 pandemic H1N1 influenza virus infections

Background: Further understanding of the clinical manifestations, hospital course and treatment options of the 2009 pandemic H1N1 influenza virus (H1N1) is needed in preparation for future outbreaks. Methods: Seventy-three children with polymerase-chain-reaction-confirmed infections with H1N1 treated in a tertiary care medical center in Israel were included in the study. Clinical data were extracted from medical records, and analyzed by hospitalization status or the presence of underlying chronic medical conditions. Results: Prevalent symptoms were fever, cough and shortness of breath, with additional findings of conjunctivitis, seizures, chills, dizziness, purpuric rash and chest pain. Hospitalized patients were more likely to have shortness of breath (OR 26.7, 95% CI: 3.5-1150), abnormal lung auscultation (OR 11.6, 95% CI: 2.8-67), abnormal X-ray (OR 3.3, 95% CI: 1.1-9.6), and a chronic illness (OR 5.4, 95% CI: 1.8-17), compared with non-hospitalized ones. Disease manifestations were similar between children with or without chronic diseases. Only two (2.7%) children required intensive care, and no deaths were recorded. A high rate (18%) of thrombocytopenia was found. One child had rapid symptom resolution after intravenous immunoglobulin treatment. Conclusion: H1N1 infection follows a mild course, even in the presence of severe underlying diseases. Abnormal respiratory findings and the presence of a chronic disease probably contributed to the decision to hospitalize patients. A rapid resolution of H1N1 symptoms after intravenous immunoglobulin treatment warrants further study, and could be a possible therapeutic option for severe cases.