PLoS One
http://www.plosone.org/
[Accessed 14 May 2016]

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Research Article
Population-Level Impact of Ontario’s Infant Rotavirus Immunization Program: Evidence of Direct and Indirect Effects
Sarah E. Wilson, Laura C. Rosella, Jun Wang, Nicole Le Saux, Natasha S. Crowcroft, Tara Harris, Shelly Bolotin, Shelley L. Deeks
| published 11 May 2016 | PLOS ONE
http://dx.doi.org/10.1371/journal.pone.0154340
Abstract
Objective
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.
Methods
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.
Results
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.
Conclusions
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.