Figure 1: Epidemiology of the pandemic influenza A (H1N1-2009) in Hong Kong and the Netherlands. (a) Introduction of imported confirmed cases in Hong Kong followed by an increase in local (indigenous) confirmed cases from May–June, 2009 [25]. (b) The hospitalization rates of the influenza A (H1N1-2009) in Amsterdam, Rotterdam and Zeeland from August–December, 2009 [26]. Weekly numbers of hospitalizations are divided by the population size in each locality.