CDC: Latest on H1N1

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

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.

Thirty-seven states are reporting widespread influenza activity at this time. They are: Alabama, Alaska, Arizona, Arkansas, California, Colorado, Delaware, Florida, Georgia, Idaho, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maryland, Minnesota, Mississippi, Missouri, Nebraska, Nevada, New Hampshire, New Mexico, New York, North Carolina, Ohio, Oklahoma, Oregon, Pennsylvania, South Carolina, South Dakota, Texas, Tennessee, Virginia, Washington, and Wyoming. Any reports of widespread influenza activity in September and October are very unusual.

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 – October 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 has increased and now exceeds what is normally expected at this time of year. In addition, 19 flu-related pediatric deaths were reported this week; 16 of these deaths were confirmed 2009 H1N1 and 3 were unsubtyped influenza A and likely to be 2009 H1N1. A total of 76 laboratory confirmed 2009 H1N1 pediatric deaths have been reported to CDC since April.