Evaluation of the Impact of a Rotavirus Vaccine Program on Pediatric Acute Gastroenteritis Hospitalizations: Estimating the Overall Effect Attributable to the Program as a Whole, and as a Per-Unit Change in Rotavirus Vaccine Coverage

Abstract

Estimation of the overall effect of a vaccine program is essential, but the effect is typically estimated for a whole program. We estimate the overall effect of the Quebec rotavirus vaccine program launched in November 2011, and the effect for each 10% increase in rotavirus vaccine coverage on pediatric, all-cause acute gastroenteritis hospitalizations. We implemented negative binomial regressions adjusted for seasonality, long-term trends, and infection dynamics, to estimate the effect of the vaccine program as: 1) a dichotomous variable, representing program presence/absence, and linear term to account for changes in trend in the post-program period, or 2) a continuous variable, representing rotavirus vaccine coverage. Using exposure 1), the vaccine program was associated with a 51.2% (95% confidence interval (CI): 28.5, 66.7) relative decline in adjusted weekly all-cause acute gastroenteritis hospitalization rates as of December 28, 2014. Using exposure 2), a 10% increase in rotavirus ≥1-dose coverage was associated with a 7.1% (95% CI: 3.5, 10.5) relative decline in adjusted weekly rates, with maximum coverage of 87.0% associated with a 47.2% (95% CI: 26.9, 61.9) relative decline. Estimation of the overall effect attributable to a change in vaccine coverage may be a useful addition to standard measurement of the overall effect.