2009 H1N1 Flu:

Key Flu Indicators

Each week CDC analyzes information about influenza disease activity in the United States and publishes findings of key flu indicators in a report called FluView. During the week of September 20-26, 2009, a review of the key indicators found that influenza activity remained elevated in the United States. Below is a summary of the most recent key indicators:

· Visits to doctors for influenza-like illness (ILI) continued to increase in some areas of the country, and overall, are higher than levels expected for this time of the year.

· Total influenza hospitalization rates for laboratory-confirmed influenza are higher than expected for this time of year for adults and children. And for children 5-17 and adults 18-49 years of age, hospitalization rates from April – September 2009 exceed average flu season rates (for October through April).

· The proportion of deaths attributed to pneumonia and influenza (P&I) based on the 122 Cities Report was low and within the bounds of what is expected at this time of year. However, 60 pediatric deaths related to 2009 H1N1 flu have been reported to CDC since April 2009, including 11 deaths reported this week.

· Twenty-seven states are reporting widespread influenza activity at this time. They are: Alabama, Alaska, Arizona, Arkansas, California, Colorado, Delaware, Florida, Georgia, Illinois, Indiana, Kansas, Kentucky, Louisiana, Maryland, Minnesota, Mississippi, New Mexico, North Carolina, Ohio, Oklahoma, Pennsylvania, Texas, Tennessee, Virginia, Washington, and Wyoming. Any reports of widespread influenza activity in September are very unusual.

· Almost all of the influenza viruses identified so far are 2009 H1N1 influenza A viruses. These viruses remain similar to the virus chosen for the 2009 H1N1 vaccine, and remain susceptible to the antiviral drugs oseltamivir and zanamivir with rare exception.