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Table 1 Alert criteria for 2009 H1N1 pandemic general descriptions

From: Event-based internet biosurveillance: relation to epidemiological observation

Alert Description Date of creation
Alert 1 Large increase in case count (ie. resurgence, 50% increase in new cases from previous week) November 5, 2009 (week 45)
Alert 2 Large increase in fatalities (ie. 50% increase in fatalities from previous week) October 1, 2009 (week 40)
Alert 3 Confirmed cases or fatalities in healthcare workers, military personnel and/or national officials July 7, 2009 (week 28)
  Cluster (>3) military personnel, health care workers and/or national officials November 5, 2009 (week 45)
Alert 4 Fatalities in cases with no underlying health conditions July 9, 2009 (week 28)
Alert 5 Severe manifestation, co-infection, re-infection (ie. encephalitis, atypical pneumonia, ICU admission with ventilator support, etc.) July 30, 2009 (week 31)
Alert 6 Reports of overwhelmed ICUs and ventilator shortages as a result of 2009 – H1N1 Influenza infection July 30, 2009 (week 31)
  Hospital/clinic infrastructure strain or collapse October 1, 2009 (week 40)
Alert 7 Human-to-swine or swine-to-human transmission July 9, 2009 (week 28)
Alert 8 Infection in species other than human or swine July 7, 2009 (week 28)
Alert 9 Anti-viral resistance/failure; Non-traditional treatments July 7, 2009 (week 28)
Alert 10 Virus mutation/reassortment July 7, 2009 (week 28)
Alert 11 Vaccine failure, severe reaction, or black market sales August 31, 2009 (week 36)
Alert 12 Massive release of antiviral or vaccine stockpile July 7, 2009 (week 28)
Alert 13 Health policy change July 9, 2009 (week 28)
Alert 14 Food safety (ie. economic loss due to suspected or feared food product contamination) July 7, 2009 (week 28)
Alert 15 Border closures July 9, 2009 (week 28)