title: Population-Level Impact of Ontario's Infant Rotavirus Immunization Program: Evidence of Direct and Indirect Effects.
abstract: To evaluate the direct and indirect population impact of rotavirus (RV) immunization on hospitalizations and emergency department (ED) visits for acute gastroenteritis (AGE) in Ontario before and after the publicly-funded RV immunization program.
  
  
  
  Administrative data was used to identify ED visits and hospitalizations for all Ontarians using ICD-10 codes. We used two outcome definitions: RV-specific AGE (RV-AGE) and codes representing RV-, other viral and cause unspecified AGE ("overall AGE"). The pre-program and public program periods were August 1, 2005 to July 31, 2011; and August 1, 2011 to March 31, 2013, respectively. A negative binominal regression model that included the effect of time was used to calculate rates and rate ratios (RRs) and 95% confidence intervals (CIs) for RV-AGE and overall AGE between periods, after adjusting for age, seasonality and secular trends. Analyses were conducted for all ages combined and age stratified.
  
  
  
  Relative to the pre-program period, the adjusted RRs for RV-AGE and overall AGE hospitalizations in the public program period were 0.29 (95%CI: 0.22-0.39) and 0.68 (95%CI: 0.62-0.75), respectively. Significant reductions in RV-AGE hospitalizations were noted overall and for the following age bands: < 12 months, 12-23 months, 24-35 months, 3-4 years, and 5-19 years. Significant declines in overall AGE hospitalizations were observed across all age bands, including older adults > = 65 years (RR 0.80, 95%CI: 0.72-0.90). The program was associated with adjusted RRs of 0.32 (95% CI: 0.20-0.52) for RV-AGE ED visits and 0.90 (95% CI: 0.85-0.96) for overall AGE ED visits.
  
  
  
  This large, population-based study provides evidence of the impact of RV vaccine in preventing hospitalizations and ED visits for RV-AGE and overall AGE, including herd effects.
authors.affiliation: Public Health Ontario, Toronto, Ontario, Canada.|Dalla Lana School of Public Health, University of Toronto, Toronto, Ontario, Canada.|Institute for Clinical Evaluative Sciences, Toronto, Ontario, Canada.
authors.forename: Sarah E
authors.identifier: 0000-0002-8239-0094
authors.initials: SE
authors.lastname: Wilson
authors.affiliation: Public Health Ontario, Toronto, Ontario, Canada.|Dalla Lana School of Public Health, University of Toronto, Toronto, Ontario, Canada.|Institute for Clinical Evaluative Sciences, Toronto, Ontario, Canada.
authors.forename: Laura C
authors.initials: LC
authors.lastname: Rosella
authors.affiliation: Public Health Ontario, Toronto, Ontario, Canada.
authors.forename: Jun
authors.initials: J
authors.lastname: Wang
authors.affiliation: Division of Infectious Disease, Children's Hospital of Eastern Ontario, Ottawa, Ontario, Canada.|Department of Pediatrics, University of Ottawa, Ottawa, Ontario, Canada.
authors.forename: Nicole
authors.initials: N
authors.lastname: Le Saux
authors.affiliation: Public Health Ontario, Toronto, Ontario, Canada.|Dalla Lana School of Public Health, University of Toronto, Toronto, Ontario, Canada.|Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Natasha S
authors.initials: NS
authors.lastname: Crowcroft
authors.affiliation: Public Health Ontario, Toronto, Ontario, Canada.
authors.forename: Tara
authors.initials: T
authors.lastname: Harris
authors.affiliation: Public Health Ontario, Toronto, Ontario, Canada.|Dalla Lana School of Public Health, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Shelly
authors.initials: S
authors.lastname: Bolotin
authors.affiliation: Public Health Ontario, Toronto, Ontario, Canada.|Dalla Lana School of Public Health, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Shelley L
authors.initials: SL
authors.lastname: Deeks
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D002675:Child, Preschool; D004636:Emergency Service, Hospital / Q000191:economics / Q000706:statistics & numerical data*; D005260:Female; D005759:Gastroenteritis / Q000453:epidemiology / Q000276:immunology / Q000517:prevention & control* / Q000821:virology; D006760:Hospitalization / Q000191:economics / Q000706:statistics & numerical data*; D006801:Humans; D017589:Immunization Programs; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D032541:Mass Vaccination / Q000458:organization & administration*; D008875:Middle Aged; D009864:Ontario / Q000453:epidemiology; D012044:Regression Analysis; D012401:Rotavirus / Q000276:immunology; D012400:Rotavirus Infections / Q000453:epidemiology / Q000276:immunology / Q000517:prevention & control* / Q000821:virology; D022243:Rotavirus Vaccines / Q000008:administration & dosage*; D014613:Vaccines, Attenuated
chemical_list: D022243:Rotavirus Vaccines; D014613:Vaccines, Attenuated