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H1N1 Flu (Swine Flu)

2009 H1N1 Flu: Situation Update

November 23, 2009, 11:30 AM

U.S. Situation Update

Weekly Flu Activity Estimates

U.S. Patient Visits Reported for Influenza-like Illness (ILI)

U.S. Influenza-like Illness (ILI) Reported by Regions

International
Situation Update

Map of International
Activity Estimates
(Including 2009 H1N1 Flu)

Key Flu Indicators

November 20, 2009, 2:30 PM

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 November 8-14, 2009, influenza activity decreased across all key indicators, but overall remained very high for this time of year. Below is a summary of the most recent key indicators:

• Visits to doctors for influenza-like illness (ILI) nationally decreased again this week over last week. This is the third consecutive week of national decreases in ILI after four consecutive weeks of sharp increases. (All regions showed declines in ILI.) While ILI declined overall nationally, visits to doctors for influenza-like illness remain high.
• Influenza hospitalization rates are beginning to decline but remain higher than expected for this time of year. Hospitalization rates continue to be highest in younger populations with the highest hospitalization rate reported in children 0-4 years old.
• The proportion of deaths attributed to pneumonia and influenza (P&I) based on the 122 Cities Report decreased slightly but is still higher than what is expected for this time of year and has remained elevated for seven weeks now. In addition, 21 flu-related pediatric deaths were reported this week: 15 of these deaths were associated with laboratory confirmed 2009 H1N1; 6 were influenza A viruses, but were not subtyped. Since April 2009, CDC has received reports of 171 laboratory-confirmed pediatric 2009 H1N1 deaths, one influenza B death, and another 28 pediatric deaths that were laboratory confirmed as influenza, but the flu virus subtype was not determined. (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.
• Forty-three states are reporting widespread influenza activity at this time; a decline of three states from last week. They are: Alabama, Alaska, Arizona, Arkansas, California, Colorado, Connecticut, Delaware, Florida, Georgia, Idaho, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Maryland, Massachusetts, Michigan, Minnesota, Missouri, Montana, Nevada, New Hampshire, New Jersey, New Mexico, New York, North Carolina, Ohio, Oklahoma, Oregon, Pennsylvania, Rhode Island, South Dakota, Tennessee, Utah, Vermont, Virginia, Washington, West Virginia, and Wisconsin.
• 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
  The Southern Hemisphere is in the middle of its flu season, and we have reports of what is happening there
• 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

Key Flu Indicators

November 20, 2009, 2:30 PM

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 November 8-14, 2009, influenza activity decreased across all key indicators, but overall remained very high for this time of year. Below is a summary of the most recent key indicators:

• Visits to doctors for influenza-like illness (ILI) nationally decreased again this week over last week. This is the third consecutive week of national decreases in ILI after four consecutive weeks of sharp increases. (All regions showed declines in ILI.) While ILI declined overall nationally, visits to doctors for influenza-like illness remain high.
• Influenza hospitalization rates are beginning to decline but remain higher than expected for this time of year. Hospitalization rates continue to be highest in younger populations with the highest hospitalization rate reported in children 0-4 years old.
• The proportion of deaths attributed to pneumonia and influenza (P&I) based on the 122 Cities Report decreased slightly but is still higher than what is expected for this time of year and has remained elevated for seven weeks now. In addition, 21 flu-related pediatric deaths were reported this week: 15 of these deaths were associated with laboratory confirmed 2009 H1N1; 6 were influenza A viruses, but were not subtyped. Since April 2009, CDC has received reports of 171 laboratory-confirmed pediatric 2009 H1N1 deaths, one influenza B death, and another 28 pediatric deaths that were laboratory confirmed as influenza, but the flu virus subtype was not determined. (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.
• Forty-three states are reporting widespread influenza activity at this time; a decline of three states from last week. They are: Alabama, Alaska, Arizona, Arkansas, California, Colorado, Connecticut, Delaware, Florida, Georgia, Idaho, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Maryland, Massachusetts, Michigan, Minnesota, Missouri, Montana, Nevada, New Hampshire, New Jersey, New Mexico, New York, North Carolina, Ohio, Oklahoma, Oregon, Pennsylvania, Rhode Island, South Dakota, Tennessee, Utah, Vermont, Virginia, Washington, West Virginia, and Wisconsin.
• 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
  The Southern Hemisphere is in the middle of its flu season, and we have reports of what is happening there
• 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