Changes in Childhood Diarrhea Incidence in Nicaragua Following 3 Years of Universal Infant Rotavirus Immunization

Background—While the pentavalent rotavirus vaccine was highly efficacious against rotavirus diarrhea in clinical trials, the vaccine’s effectiveness under field conditions in the developing world is unclear. In October, 2006, Nicaragua became the first developing nation to implement universal infant immunization with the pentavalent rotavirus vaccine. To assess the impact of the immunization program, we examined the incidence of diarrhea episodes between 2003 and 2009 among children in the state of Leon, Nicaragua. Methods—We extracted data on diarrhea episodes from health ministry records. We used scaled Poisson regression models to estimate diarrhea incidence rate ratios (IRR) for the period following the program’s implementation to the period before implementation. Results—Following implementation of the immunization program, diarrhea episodes among infants were reduced (IRR 0.85, 95% confidence interval [CI] 0.71–1.02) during the rotavirus season, but appear to have increased during other months. Conclusions—While the immunization program appears effective in reducing diarrhea episodes during the rotavirus season, a large burden of diarrhea persists during the remainder of the year.