Trends in severe gastroenteritis among young children according to socio-economic characteristics before and after implementation of a rotavirus vaccination program in Quebec.

OBJECTIVES Following implementation of a publicly funded rotavirus immunization program in Quebec (Canada) in 2011, its impact on gastroenteritis hospitalization rates, a proxy for severe gastroenteritis, was assessed. METHODS Using a tertiary hospital database and a regional vaccination registry, temporal trends in rates of hospitalization for acute gastroenteritis (AGE) and rotavirus gastroenteritis before the age of five years and rotavirus vaccine coverage were examined from June 2004 through May 2014 in a large retrospective birth cohort in the Eastern Townships region. The mean annual AGE hospitalization rate in post-program years (2011/2012-2013/2014) was compared with that in pre-program years (2004/2005-2010/2011) overall and according to the characteristics of the children, families and residential neighbourhoods at birth. RESULTS The AGE hospitalization rate significantly decreased from 81/10,000 in the pre-program period to 46/10,000 in the post-program period (relative reduction = 43%). Following implementation of the program, vaccine coverage rapidly increased and reached 81%. All socio-economic categories showed a reduced hospitalization rate in the post-program period, but the lowest relative reductions were observed in children living in neighbourhoods with higher rates of unemployment, low-income families and single mothers. However, these disadvantaged subgroups did not have lower vaccine coverage. CONCLUSIONS Three years following its introduction in a universal vaccination program, rotavirus vaccine significantly reduced severe gastroenteritis in young children. Despite similar vaccine coverage among all children, disadvantaged socio-economic groups appeared to have a less pronounced AGE reduction, suggesting that factors other than vaccination could partially influence the reduction of gastroenteritis morbidity in young children.