During the week of October 11-17, 2009, the Center for Disease Control found that influenza activity continued to increase in the United States from the previous week.
Below is a summary of the most recent key indicators:
* Visits to doctors for influenza-like illness (ILI) increased steeply since last week in the United States, and overall, are much higher than what is expected for this time of the year. ILI activity now is higher than what is seen during the peak of many regular flu seasons.
* Total influenza hospitalization rates for laboratory-confirmed flu are climbing and are higher than expected for this time of year.
* The proportion of deaths attributed to pneumonia and influenza (P&I) based on the 122 Cities Report has increased and has been higher than what is expected at this time of year for two weeks. In addition, 11 flu-related pediatric deaths were reported this week; 9 of these deaths were confirmed 2009 H1N1, and two were influenza A viruses, but were not subtyped. Since April 2009, CDC has received reports of 95 laboratory-confirmed pediatric 2009 H1N1 deaths and another 7 pediatric deaths that were laboratory confirmed as influenza, but where the flu virus subtype was not determined.
* Forty-six 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, Maine, Maryland, Massachusetts, Michigan, Minnesota, Mississippi, Missouri, Montana, Nebraska, Nevada, New Hampshire, New Mexico, New York, North Carolina, North Dakota, Ohio, Oklahoma, Oregon, Pennsylvania, Rhode Island, South Dakota, Tennessee, Texas, Utah, Vermont, Virginia, Washington, West Virginia, Wisconsin, and Wyoming. This many reports of widespread activity are unprecedented during seasonal flu.
* 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.
