Early experience of the pandemic influenza H1N1 2009 epidemic in Taiwan

A novel influenza H1N1 began in March 2009, rapidly spread, and then became a pandemic outbreak. Diagnosis by polymerase chain reaction result was not always available because of a surge in workload and therefore clinical diagnosis became important. However, clinical differences between the patients infected by the novel H1N1 virus and those infected by the influenza-like non-novel H1N1 have not been reported. This study was conducted to compare the demographic background, clinical manifestations, and laboratory findings between novel H1N1 influenza infections and other non-novel H1N1 infections.