Direct, Indirect, Total, and Overall Effectiveness of the Rotavirus Vaccines for the Prevention of Gastroenteritis Hospitalizations in Privately Insured US Children, 2007-2010

We demonstrate how direct, indirect, total, and overall effectiveness estimates and absolute benefits of rotavirus vaccines vary through the years following vaccine introduction. Privately insured US children in a large claims database were followed from age 8 months until they 1) experienced a hospitalization for rotavirus or acute gastroenteritis; 2) lost continuous health plan enrollment; 3) turned 20 months of age; or 4) reached the end of the study period. Vaccine effectiveness estimates in preventing rotavirus and acute gastroenteritis hospitalizations were estimated using Cox proportional hazards regression, stratified by calendar year and adjusted for birth month. Incidence rate differences were estimated to determine the absolute number of gastroenteritis hospitalizations prevented in the cohort. Among 905,718 children, 51%, 66%, 80%, and 86% received 1 or more doses of rotavirus vaccine in each year from 2007 to 2010. The direct vaccine effectiveness of 1 or more doses of rotavirus vaccine in preventing rotavirus gastroenteritis hospitalizations ranged from 87% to 92% each year. Accounting for indirect protection increased estimates of vaccine effectiveness by an additional 3%-8% among those vaccinated. Failing to account for population-level vaccine benefits in 2010, when circulation of rotavirus was low, could underestimate the sustained impact of the vaccine program.