The U.S. flu season is slowly winding down after hitting some states hard

The U.S. flu season has hit some states hard. California has already confirmed 202 influenza-related deaths--almost double the toll in the entire 2012-2013 flu season--and is investigating a further 41 cases. Now, though, there are signs the virus is letting up, with multiple influenza activity indicators in decline.

In the latest edition of its influenza surveillance report, FluView, the Centers for Disease Control and Prevention (CDC) reports the downward trend first seen two weeks ago is continuing. The percentage of respiratory samples testing positive for the flu virus, number of states reporting high influenza activity and the share of deaths related to the illness all fell. While the declines are fairly small--the proportion of samples testing positive for flu is down 7%--the trend is consistent across multiple indicators.

High levels of flu activity were reported by 7 states, down from 10 last week, with the south-central region experiencing the most cases. Arkansas, Kansas, Oklahoma and Texas were at the top of CDC's influenza-like illness activity scale. While Alabama, Louisiana, Vermont and Virginia all dropped off the top rung over the past week, across the Atlantic in Europe flu activity is still on the rise. Incidence of influenza rose in 17 of the 29 countries that reported data, although only Greece suffered a high intensity of flu.

H1N1 has been the dominant strain in both the U.S. and Europe, accounting for 96% of all subtyped cases in the former. The H1N1 virus has hit middle-aged adults particularly hard, with two-thirds of the deaths in California being in the 40- to 60-year-old age bracket. Declining activity suggests the flu season has peaked in most of the U.S., but authorities are warning a resurgence of the virus is possible. "The flu is unpredictable," Dr. James Watt, an epidemiologist for the state of California, told the Merced Sun-Star.

- view CIDRAP's coverage
- here's the CDC data
- check out the European report (PDF)
- read the Sun-Star article