Temporal Changes in Pediatric Gastroenteritis after Rotavirus Vaccination in Quebec.

Background: Rotavirus and norovirus are among the leading causes of pediatric gastroenteritis. We examined the relative burden of pediatric gastroenteritis by etiology and compared the clinical severity of rotavirus and norovirus cases after the November 2011 implementation of publicly funded rotavirus vaccination program in Quebec.
Methods: Prospective, active surveillance for acute gastroenteritis among children aged 8 weeks to less than 3 years of age was implemented at 3 hospitals. Participant demographics, clinical histories and stools were collected; stools were tested for rotavirus, norovirus and sapovirus. Risk and absolute differences of several clinical severity outcomes were compared by etiology with adjustment for patient age.
Results: From February 2012 to May 2014, 734 eligible active surveillance patients were recruited, and stools from 705 (96.0%) were tested and included in study analyses. Of these, 20.4% [95% confidence interval (CI): 16.5-24.3%] were rotavirus positive and 25.5% (95% CI: 21.3-29.8%) were norovirus positive, representing a difference of 5.1% (95% CI: 0.1-10.1%). When stratified by year, rotavirus and norovirus prevalence were similar from June 2012 to May 2013, but rotavirus prevalence was 21.4% (95% CI: 14.3-28.5%) lower than norovirus from June 2013 to May 2014. On average, rotavirus patients were more likely to be febrile, dehydrated, hospitalized and report more diarrheal episodes at the height of illness in comparison with norovirus patients of the same age.
Conclusions: Norovirus infections were more prevalent than rotavirus infections among pediatric gastroenteritis cases hospitalized or seeking emergency care. Rotavirus cases were, on average, more clinically severe than norovirus cases among participants of the same age.