Clinical manifestations of influenza A and B in children and adults at a tertiary hospital in Korea during the 2011–2012 season

This study aims to evaluate and compare the epidemiological patterns and clinical courses of influenza A and B among children and adults. For this purpose, we retrospectively reviewed the medical records of 809 children and 271 adolescents/adults with laboratory-confirmed influenza between October 2011 and May 2012 at a tertiary-care hospital. Children with influenza B presented with high fever (body temperature >39°C), sputum production, diarrhea, nausea/vomiting, and myalgia more frequently than those with influenza A. Children with influenza B also showed longer intervals from symptom onset to the initiation of antivirals and higher rates of antibiotic prescription and hospitalization than those with influenza A. Adults aged 20–59 years accounted for approximately 16% and 20% of patients with influenza A and B, respectively. Although clinical manifestations and outcomes were similar between adult patients with influenza A and those with influenza B, influenza B may cause substantial disease burden among not only children but also socially active adults aged 20–59 years.