Figure 6.20 Swine flu, United States, 2009–10. Values of the swash model parameters, R0A and t–LE, for the first 39 weeks (July–October) of each of the influenza seasons, 2004–5 to 2008–9, and for the first swine flu season, 2009–10 at three geographical scales. (A) 122 cities comprising the ILINet (influenza-like illnesses) PI (pneumonia–influenza) mortality dataset. (B) Fifty states. (C) Ten United States Department of Health and Human Services regions.

Source: Data from Centers for Disease Control, available from and