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 2008-2009 Influenza Season

• Week Ending November 14, 2009 (MMWR Week 45) [pdf 383k]
• Week Ending November 7, 2009 (MMWR Week 44) [pdf 306k]
• Week Ending October 31, 2009 (MMWR Week 43) [pdf 377k]
• Week Ending October 24, 2009 (MMWR Week 42) [pdf 303k]
• Week Ending October 17, 2009 (MMWR Week 41) [pdf 298k]
• Week Ending October 10, 2009 (MMWR Week 40) [pdf 361k]
• Week Ending October 3, 2009 (MMWR Week 39) [pdf 268k]
• Week Ending September 26, 2009 (MMWR Week 38) [pdf 268k]
• Week Ending September 19, 2009 (MMWR Week 37) [pdf 227k]
• Week Ending September 12, 2009 (MMWR Week 36) [pdf 180k]
• Week Ending September 5, 2009 (MMWR Week 35) [pdf 216k]
• Week Ending August 29, 2009 (MMWR Week 34) [pdf 217k]
• Week Ending August 22, 2009 (MMWR Week 33) [pdf 429k]
• Week Ending August 15, 2009 (MMWR Week 32) [pdf 175k]
• Week Ending August 8, 2009 (MMWR Week 31) [pdf 175k]
• Week Ending August 1, 2009 (MMWR Week 30) [pdf 175k]
• Week Ending July 25, 2009 (MMWR Week 29) [pdf 174k]
• Week Ending July 18, 2009 (MMWR Week 28) [pdf 174k]
• Week Ending July 11, 2009 (MMWR Week 27) [pdf 174k]
• Week Ending July 4, 2009 (MMWR Week 26) [pdf 174k]
• Week Ending June 27, 2009 (MMWR Week 25) [pdf 174k]
• Week Ending June 20, 2009 (MMWR Week 24) [pdf 173k]
  
• Week Ending June 13, 2009 (MMWR Week 23) [pdf 214k]
• Week Ending June 6, 2009 (MMWR Week 22) [pdf 172k]
• Week Ending May 30, 2009 (MMWR Week 21) [pdf 172k]
• Week Ending May 23, 2009 (MMWR Week 20) [pdf 214k]
• Week Ending May 16, 2009 (MMWR Week 19) [pdf 214k]
• Week Ending May 9, 2009 (MMWR Week 18) [pdf 188k]
• Week Ending May 2, 2009 (MMWR Week 17) [pdf 446k]
• Week Ending April 18, 2009 (MMWR Week 15) [pdf 587k]
• Week Ending April 11, 2009 (MMWR Week 14) [pdf 499k]
• Week Ending April 4, 2009 (MMWR Week 13) [pdf 486k]
• Week Ending March 28, 2009 (MMWR Week 12) [pdf 580k]
• Week Ending March 21, 2009 (MMWR Week 11) [pdf 579k]
• Week Ending March 14, 2009 (MMWR Week 10) [pdf 579k]
• Week Ending March 7, 2009 (MMWR Week 9) [pdf 581k]
• Week Ending February 28, 2009 (MMWR Week 8) [pdf 581k]
• Week Ending February 21, 2009 (MMWR Week 7) [pdf 892k]
• Week Ending February 14, 2009 (MMWR Week 6) [pdf 490k]
• Week Ending February 7, 2009 (MMWR Week 5) [pdf 402k]
• Week Ending January 31, 2009 (MMWR Week 4) [pdf 491k]
• Week Ending January 24, 2009 (MMWR Week 3) [pdf 492k]
• Week Ending January 17, 2009 (MMWR Week 2) [pdf 495k]
• Week Ending January 10, 2009 (MMWR Week 1) [pdf 399k]
• Week Ending January 3, 2009 (MMWR Week 53) [pdf 401k]
• Week Ending December 27, 2008 (MMWR Week 52) [pdf 375k]
• Week Ending December 20, 2008 (MMWR Week 51) [pdf 490k]
• Week Ending December 13, 2008 (MMWR Week 50) [pdf 490k]
• Week Ending December 6, 2008 (MMWR Week 49) [pdf 490k]
• Week Ending November 29, 2008 (MMWR Week 48) [pdf 342k]
• Week Ending November 22, 2008 (MMWR Week 47) [pdf 488k]
• Week Ending November 15, 2008 (MMWR Week 46) [pdf 488k]
• Week Ending November 8, 2008 (MMWR Week 45) [pdf 487k]
• Week Ending November 1, 2008 (MMWR Week 44) [pdf 489k]
• Week Ending October 25, 2008 (MMWR Week 43) [pdf 489k]
• Week Ending October 18, 2008 (MMWR Week 42) [pdf 487k]
• Week Ending October 11, 2008 (MMWR Week 41) [pdf 486k]
• Week Ending October 4, 2008 (MMWR Week 40) [pdf 638k]

Resources

• ILI Activity Levels [pdf 12k]
• MMWR Weeks [pdf 27k]
• National Influenza Activity Report

Archives