Figure 4

Multi-scale spatial patterns of H1N1 influenza occurrence in the US. Each of the spatial pattern W discovered from NMF can examine how the flu spread throughout the US (left hand panels). The nation wide panels depict how W₁ pattern is widespread throughout the US followed by progressively moving down south (W₄ ). The spatial pattern W₅ depicts flu prevalence only within large metropolitan areas and southern Florida. One can focus further into state-wide patterns (middle panel) and examine how ILI-patterns affect the state of Tennessee and towards specific metropolitan areas (e.g., Memphis in Tennessee, right most panels) and capture minor variations in the ILI-patterns according to different zip-codes. These differences also allow one to identify bridge regions (highlighted by red and magenta circles) that show more than two ILI-patterns in the same zip code. These analyses can be further extended out towards the state and nation-wide areas.