Clades of A/H1N1 (A–H, Figure 1) and A/H3N2 (a, b, s1, s2, s3, s4) influenza virus that co-circulate among multiple localities by epidemic week.

Localities listed by longitudinal ordinates (°W) from west to east. The total number of clades that co-circulate in a given locality over the entire time period listed in the far right column. Week 1 begins 12/3/2006; week 2–12/10/06; week 3–12/17/06; week 4–12/24/06; week 5–12/31/06; week 6–1/7/2007; week 7–1/14/07; week 8–1/21/07; week 9–1/28/07; week 10–2/4/07; week 11–2/11/07; week 12–2/18/07; week 13–2/25/07; week 14–3/4/07; week 15–3/11/07.