Impact of rotavirus vaccine on acute gastroenteritis emergency department visits and hospitalizations in a highly-vaccinated urban cohort

摘要

Background: Rotavirus vaccines (RVV) have significantly reduced rotavirus disease in children over the past 4 years in the United States. In this study, we describe the impact of RVV in preventing acute gastroenteritis (AGE) hospital encounters in a highly-vaccinated urban pediatric network during the 2007 and 2008 rotavirus seasons. Methods: We used 5 urban practices from a practice-based network to conduct a retrospective cohort study comparing the numbers of AGE emergency department (ED) visits and hospitalizations in RVV-immunized (exposed) and non-immunized (unexposed) children during the first 2 full seasons following RVV introduction. We determined incident rate ratios (IRR), using Poisson regression, and vaccine effectiveness for each outcome. Results: The 2007 and 2008 cohorts were analyzed separately. 62% of the 2007 cohort was vaccinated and 88% of the 2008 cohort. AGE hospitalizations were significantly reduced among RVV-immunized children from the 2007 cohort in the 2008 season with vaccine effectiveness of 67%. Sub-analysis of this cohort by age revealed that RVV was most protective against hospitalizations in the youngest age group (IRR = 0.21, 95% CI (0.06, 0.82). A trend toward protection against hospitalization was detected for both cohorts in the first season following immunization that did not reach a statistically significant level. For AGE ED visits, no significant difference was seen between RVV-immunized and non-immunized children in either cohort, although there was a trend toward protection (IRR’s: 0.67 - 0.7). Conclusions: RVV was highly effective in preventing AGE hospitalizations for a subset of our cohort in 2008. Given reports of RVV effectiveness, we hypothesize that herd immunity is responsible for the inability to detect a significant difference between RVV-immunized and non-immunized children in our highly- vaccinated cohort.