title: School absenteeism as an adjunct surveillance indicator: experience during the second wave of the 2009 H1N1 pandemic in Quebec, Canada.
abstract: BACKGROUND
  A school absenteeism surveillance system was implemented in the province of Quebec, Canada during the second wave of the 2009 H1N1 pandemic. This paper compares this surveillance approach with other available indicators.
  
  
  METHODS
  All (3432) elementary and high schools from Quebec were included. Each school was required to report through a web-based system any day where the proportion of students absent for influenza-like illness (ILI) exceeded 10% of current school enrolment.
  
  
  RESULTS
  Between October 18 and December 12 2009, 35.6% of all schools met the 10% absenteeism threshold. This proportion was greater in elementary compared to high schools (40% vs 19%) and in smaller compared to larger schools (44% vs 22%). The maximum absenteeism rate was reached the first day of reporting or within the next two days in 55% and 31% of schools respectively. The first reports and subsequent peak in school absenteeism provincially preceded the peak in paediatric hospitalization by two and one weeks, respectively. Trends in school surveillance otherwise mirrored other indicators.
  
  
  CONCLUSIONS
  During a pandemic, school outbreak surveillance based on a 10% threshold appears insufficient to trigger timely intervention within a given affected school. However, school surveillance appears well-correlated and slightly anticipatory compared to other population indicators. As such, school absenteeism warrants further evaluation as an adjunct surveillance indicator whose overall utility will depend upon specified objectives, and other existing capacity for monitoring and response.
authors.affiliation: Department of Social and Preventive Medicine, Université Laval, Quebec City, Quebec, Canada.
authors.forename: Christelle Aïcha
authors.initials: CA
authors.lastname: Kom Mogto
authors.forename: Gaston
authors.initials: G
authors.lastname: De Serres
authors.forename: Monique
authors.initials: M
authors.lastname: Douville Fradet
authors.forename: Germain
authors.initials: G
authors.lastname: Lebel
authors.forename: Steve
authors.initials: S
authors.lastname: Toutant
authors.forename: Rodica
authors.initials: R
authors.lastname: Gilca
authors.forename: Manale
authors.initials: M
authors.lastname: Ouakki
authors.forename: Naveed Zafar
authors.initials: NZ
authors.lastname: Janjua
authors.forename: Danuta M
authors.initials: DM
authors.lastname: Skowronski
mesh_terms: D000041:Absenteeism; D000293:Adolescent; D002648:Child; D004196:Disease Outbreaks; D006801:Humans; D015994:Incidence; D053118:Influenza A Virus, H1N1 Subtype / Q000235:genetics*; D007251:Influenza, Human / Q000453:epidemiology*; D015233:Models, Statistical; D058873:Pandemics; D011159:Population Surveillance / Q000379:methods*; D011792:Quebec / Q000453:epidemiology; D012574:Schools; D013334:Students; D055815:Young Adult