title: Case-based surveillance of influenza hospitalizations during 2004-2008, Colorado, USA.
abstract: Colorado became the first state to make laboratory-confirmed influenza-associated hospitalizations a case-based reportable condition in 2004. We summarized surveillance for influenza hospitalizations in Colorado during the first 4 recorded influenza seasons (2004-2008). We highlight the similarities and differences among influenza seasons; no 2 seasons were entirely the same. The 2005-06 influenza season had 2 distinct waves of activity (types A and B), the 2006-07 season was substantially later and milder, and 2007-08 had substantially greater influenza B activity. The case-based surveillance for influenza hospitalizations provides information regarding the time course of seasonal influenza activity, reported case numbers and population-based rates by age group and influenza virus type, and a measure of relative severity. Influenza hospitalization surveillance provides more information about seasonal influenza activity than any other surveillance measure (e.g., surveillance for influenza-like illness) currently in widespread use among states. More states should consider implementing case-based surveillance for influenza hospitalizations.
authors.affiliation: University of Colorado Denver, Colorado, USA.
authors.forename: Rosemary
authors.initials: R
authors.lastname: Proff
authors.forename: Ken
authors.initials: K
authors.lastname: Gershman
authors.forename: Dennis
authors.initials: D
authors.lastname: Lezotte
authors.forename: Ann-Christine
authors.initials: AC
authors.lastname: Nyquist
mesh_terms: D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D019411:Clinical Laboratory Techniques; D003120:Colorado / Q000453:epidemiology; D018563:Disease Notification / Q000379:methods / Q000706:statistics & numerical data*; D006760:Hospitalization / Q000706:statistics & numerical data*; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D009980:Influenza A virus / Q000302:isolation & purification; D009981:Influenza B virus / Q000302:isolation & purification; D007251:Influenza, Human / Q000175:diagnosis / Q000453:epidemiology* / Q000821:virology; D007755:Laboratories, Hospital; D008875:Middle Aged; D011159:Population Surveillance / Q000379:methods*; D012621:Seasons; D055815:Young Adult