Figure 1. Spatial and temporal distribution of reported cases of influenza A(H7N9) virus infection among humans, China, 2013–2014. Onset of the first case in wave 1 was February 19, 2013 (although the case was not reported until the end of March 2013); onset of the last case in wave 1 was July 27, 2013; only 4 cases occurred in May–July 2013. Onset of the first case in wave 2 was October 7; onset of the last case in our time series was April 17, 2014. A) Case onset reports across all regions. Colors indicate the 4 largest geographic clusters; black indicates all other cases. B) Spatial pattern of reported cases. Points show geodesic distance between the first reported case of influenza A(H7N9) virus infection (in Shanghai) and location of each subsequent reported case. Cases are colored by region as in panel A.