Detection of influenza epidemic by moving average regression method (Serfling method) based on the surveillance data of influenza‐like illness (ILI) during 2004–2008 in Wuxi, People’s Republic of China. Weekly proportion of ILI is calculated as the weekly counts of ILI to total patient visits. The occurrence of each important epidemic event is marked by a vertical line. Legend: Ip, the first imported influenza A (H1N1) case; Lc, the first local influenza A (H1N1) case; Sc, the outbreak of influenza A (H1N1) in school; Pk, the epidemic peak of influenza A (H1N1) in general population.