Key Flu Indicators

February 05, 2010, 11:00 AM

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 January 24-30, 2010, most key flu indicators remained about the same as during the previous week. Below is a summary of the most recent key indicators:

• Visits to doctors for influenza-like illness (ILI) nationally are low.  ILI is also looked at by Region. Of 10 regions in the United States, ILI declined or remained about the same, except for in one region of the country. In Region 10 (Alaska, Oregon, Idaho and Washington), ILI activity increased, but still remains low overall.

• Overall cumulative hospitalization rates for the 2009-10 influenza season have leveled off in all age groups and very few 2009 H1N1-laboratory confirmed hospitalizations were reported by states during the week ending January 3o.

• The proportion of deaths attributed to pneumonia and influenza (P&I) based on the 122 Cities Report decreased slightly over the previous week, but is still higher than expected for this time of year. In addition, another nine flu-related pediatric deaths were reported this week: eight of these deaths were associated with laboratory confirmed 2009 H1N1, and one death was associated with an influenza A virus for which the subtype was undetermined. Since April 2009, CDC has received reports of 321 laboratory-confirmed pediatric deaths: 272 due to 2009 H1N1, 47 pediatric deaths that were laboratory confirmed as influenza, but the flu virus subtype was not determined, and two pediatric deaths that were associated with seasonal influenza viruses. (Laboratory-confirmed deaths are thought to represent an undercount of the actual number. CDC has provided estimates about the number of 2009 H1N1 cases and related hospitalizations and deaths.

• No states reported widespread influenza activity. Six states reported regional influenza activity. They are: Alabama, Georgia, Maine, New Jersey, New Mexico and Virginia. Almost all of the influenza viruses identified so far continue to be 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.

*All data are preliminary and may change as more reports are received.

More on the Situation

• CDC Response
  A summary of CDC activities
• FluView
  A Weekly Influenza Surveillance Report Prepared by the Influenza Division.
• International Situation Update
  A summary of global 2009 H1N1 activity.
  
• Facts and Figures
  A summary of key 2009 H1N1 disease characteristics.
• Health Alert Network (HAN) Messages
• Q & A: CDC's Online Reporting

Background

• Background
  Learn about the emergence of the 2009 H1N1 virus in the United States and WHO's declaration of a novel H1N1 pandemic.
• Past Situation Updates
• Press Updates
• Other Reports and Publications