Last season's flu stats

Quick View. Oct. 23/30, 2006.

Last season, peak flu activity was less intense than in the previous three years but remained elevated for a longer time.

Overall, incidence was low from October through early January, increased in February and peaked in early March. Based on data from state and territorial epidemiologists, the flu season's high point occurred in the week ending March 11, when 25 states reported widespread activity and 16 states reported regional activity. In the previous three seasons, the peak number of states reporting activity ranged from 35 to 50.

In 2005-06, 38 states and New York City reported widespread activity at least once during the season. For 18 consecutive weeks, beginning the week ending Dec. 17, 2005, at least one state reported activity.

Regional differences were explained in part by strains in various areas. Though influenza A (H3N2) viruses predominated, influenza B had a late-season burst. Therefore, the western-most regions reported early and extended activity due to an early peak of influenza A activity from mid-December to January and a second, lesser peak of influenza B from early March to early May. In the middle and eastern regions, influenza A activity peaked later, with B strains demonstrating less activity. Thus, these regions saw a single peak of influenza virus activity in early March.