title: Hospitalization for Influenza A Versus B.
abstract: The extent to which influenza A and B infection differs remains uncertain.
  
  
  
  Using active surveillance data from the Canadian Immunization Monitoring Program Active at 12 pediatric hospitals, we compared clinical characteristics and outcomes of children ≤16 years admitted with laboratory-confirmed influenza B or seasonal influenza A. We also examined factors associated with ICU admission in children hospitalized with influenza B.
  
  
  
  Over 8 nonpandemic influenza seasons (2004-2013), we identified 1510 influenza B and 2645 influenza A cases; median ages were 3.9 and 2.0 years, respectively (P < .0001). Compared with influenza A patients, influenza B patients were more likely to have a vaccine-indicated condition (odds ratio [OR] = 1.30; 95% confidence interval [CI] = 1.14-1.47). Symptoms more often associated with influenza B were headache, abdominal pain, and myalgia (P < .0001 for all symptoms after adjustment for age and health status). The proportion of deaths attributable to influenza was significantly greater for influenza B (1.1%) than influenza A (0.4%); adjusted for age and health status, OR was 2.65 (95% CI = 1.18-5.94). A similar adjusted OR was obtained for all-cause mortality (OR = 2.95; 95% CI = 1.34-6.49). Among healthy children with influenza B, age ≥10 years (relative to <6 months) was associated with the greatest odds of ICU admission (OR = 5.79; 95% CI = 1.91-17.57).
  
  
  
  Mortality associated with pediatric influenza B infection was greater than that of influenza A. Among healthy children hosptialized with influenza B, those 10 years and older had a significant risk of ICU admission.
authors.affiliation: Division of Infectious Diseases, Department of Paediatrics, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada; dat.tran@sickkids.ca.
authors.forename: Dat
authors.initials: D
authors.lastname: Tran
authors.affiliation: Division of Infectious Diseases, Department of Paediatrics, Stollery Children's Hospital, University of Alberta, Edmonton Alberta, Canada;
authors.forename: Wendy
authors.initials: W
authors.lastname: Vaudry
authors.affiliation: Division of Infectious Diseases, Department of Paediatrics, Montreal Children's Hospital, McGill University, Montreal, Québec, Canada;
authors.forename: Dorothy
authors.initials: D
authors.lastname: Moore
authors.affiliation: Vaccine Evaluation Center, BC Children's Hospital, University of British Columbia, Vancouver, British Columbia, Canada;
authors.forename: Julie A
authors.initials: JA
authors.lastname: Bettinger
authors.affiliation: Canadian Center for Vaccinology, IWK Health Centre, Dalhousie University, Halifax, Nova Scotia, Canada;
authors.forename: Scott A
authors.initials: SA
authors.lastname: Halperin
authors.affiliation: Vaccine Evaluation Center, BC Children's Hospital, University of British Columbia, Vancouver, British Columbia, Canada;
authors.forename: David W
authors.initials: DW
authors.lastname: Scheifele
authors.affiliation: Section of Infectious Diseases, Department of Paediatrics, Alberta Children's Hospital, University of Calgary, Calgary, Alberta, Canada; and.
authors.forename: Taj
authors.initials: T
authors.lastname: Jadvji
authors.affiliation: Centre for Immunization & Respiratory Infectious Diseases, Public Health Agency of Canada, Ottawa, Canada.
authors.forename: Liza
authors.initials: L
authors.lastname: Lee
authors.affiliation: Centre for Immunization & Respiratory Infectious Diseases, Public Health Agency of Canada, Ottawa, Canada.
authors.forename: Teresa
authors.initials: T
authors.lastname: Mersereau
mesh_terms: D000293:Adolescent; D002170:Canada / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D017281:Cost of Illness; D005260:Female; D006760:Hospitalization / Q000706:statistics & numerical data*; D006776:Hospitals, Pediatric; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D009980:Influenza A virus; D009981:Influenza B virus; D007252:Influenza Vaccines; D007251:Influenza, Human / Q000175:diagnosis / Q000453:epidemiology* / Q000628:therapy; D016015:Logistic Models; D008297:Male; D062486:Public Health Surveillance; D012621:Seasons; D012720:Severity of Illness Index
chemical_list: D007252:Influenza Vaccines