Influenza Surveillance System

• Definitions of Weekly Flu Activity Levels
• Weekly Flu Activity Reports
  
  

Definitions of Weekly Flu Activity Levels

• No Activity- Indicators of influenza-like illness below state baseline¹ levels and no laboratory-confirmed² cases of influenza.
  
  
• Sporadic – Elevated indicators³ of influenza-like illness in a single county and at least one laboratory confirmed case² of influenza anywhere in the state.
  OR
  At least one laboratory-confirmed² influenza outbreak in an institution anywhere in the state
  
  
• Local – Elevated indicators³ of influenza-like illness in a single county and recent⁴ laboratory-confirmed² influenza cases from that same county.  (There may be other counties elevated above baseline¹ without laboratory-confirmed² cases.)
  OR
  Laboratory-confirmed² influenza outbreaks in two or more institutions in a single county.
  
  
• Regional --Elevated indicators³ of influenza-like illness in from two to 10 counties and recent² laboratory confirmed² influenza cases from these same counties.
  OR
  Confirmed² influenza outbreaks reported in institutions in from 2 to 10 counties.
  
  
• Widespread – Elevated indicators³ of influenza-like illness in more than 10 counties and recent⁴ laboratory-confirmed² cases of influenza.
  OR
  Influenza outbreaks in institutions in more than 10 counties and recent⁴ laboratory-confirmed² cases of influenza.

¹ Baseline refers to the level of influenza-like illness in the months when seasonal influenza virus is less likely to be circulating.  Baseline is determined by averaging the statewide percentages of ILI over a three-year period, using data only from the months of May through August.  (The calculation does not include weeks in which fewer than four counties reported any data.)

² Confirmed by viral culture or PCR testing.

³ This means at least two of the following sectors – schools, emergency departments, long-term care facilities, healthcare providers – are reporting rates of ILI above baseline levels.

⁴ Within the previous three weeks.

Influenza Activity Report 2011-2012 Influenza Season

• Week Ending February 4, 2012 (MMWR Week 5) [pdf 423k]
  Week Ending February 4, 2012 (MMWR Week 5) Graphs Only [pdf 200k]
• Week Ending January 28, 2012 (MMWR Week 4) [pdf 423k]
  Week Ending January 28, 2012 (MMWR Week 4) Graphs Only [pdf 200k]
• Week Ending January 21, 2012 (MMWR Week 3) [pdf 306k]
  Week Ending January 21, 2012 (MMWR Week 3) Graphs Only [pdf 198k]
• Week Ending January 14, 2012 (MMWR Week 2) [pdf 419k]
  Week Ending January 14, 2012 (MMWR Week 2) Graphs Only [pdf 119k]
• Week Ending January 7, 2012 (MMWR Week 1) [pdf 302k]
  Week Ending January 7, 2012 (MMWR Week 1) Graphs Only [pdf 195k]
• Week Ending December 31, 2011 (MMWR Week 52) [pdf 390k]
  Week Ending December 31, 2011 (MMWR Week 52) Graphs Only [pdf 166k]
• Week Ending December 24, 2011 (MMWR Week 51) [pdf 363k]
  Week Ending December 24, 2011 (MMWR Week 51) Graphs Only [pdf 164k]
• Week Ending December 17, 2011 (MMWR Week 50) [pdf 363k]
  Week Ending December 17, 2011 (MMWR Week 50) Graphs Only [pdf 164k]
• Week Ending December 10, 2011 (MMWR Week 49) [pdf 272k]
  Week Ending December 10, 2011 (MMWR Week 49) Graphs Only [pdf 163k]
• Week Ending December 3, 2011 (MMWR Week 48) [pdf 271k]
  Week Ending December 3, 2011 (MMWR Week 48) Graphs Only [pdf 163k]
• Week Ending November 26, 2011 (MMWR Week 47) [pdf 270k]
  Week Ending November 26, 2011 (MMWR Week 47) Graphs Only [pdf 162k]
• Week Ending November 19, 2011 (MMWR Week 46) [pdf 270k]
  Week Ending November 19, 2011 (MMWR Week 46) Graphs Only [pdf 162k]
• Week Ending November 12, 2011 (MMWR Week 45) [pdf 270k]
  Week Ending November 12, 2011 (MMWR Week 45) Graphs Only [pdf 162k]
• Week Ending November 5, 2011 (MMWR Week 44) [pdf 269k]
  Week Ending November 5, 2011 (MMWR Week 44) Graphs Only [pdf 161k]
• Week Ending October 29, 2011 (MMWR Week 43) [pdf 283k]
  Week Ending October 29, 2011 (MMWR Week 43) Graphs Only [pdf 159k]
• Week Ending October 22, 2011 (MMWR Week 42) [pdf 268k]
  Week Ending October 22, 2011 (MMWR Week 42) Graphs Only [pdf 159k]
• Week Ending October 15, 2011 (MMWR Week 41) [pdf 330k]
  Week Ending October 15, 2011 (MMWR Week 41) Graphs Only [pdf 158k]
• Week Ending October 8, 2011 (MMWR Week 40) [pdf 330k]
  Week Ending October 8, 2011 (MMWR Week 40) Graphs Only [pdf 158k]

Resources

• MMWR Weeks [pdf 27k]
• National Influenza Activity Report
• Severe and Fatal Influenza Associated Pediatric Mortality [pdf 534k]

Archives