DescriptionEstimates of the clinical and financial burden of RV disease among children aged less than 5 years before and after the introduction of the vaccines stratified by various age groups, particularly during recent years’ RV seasons, are limited. Published studies to date using real-world practice data have included only the Rotateq vaccine, and have not included Medicaid low-income population1. Additionally, there is no published study that looked at the effectiveness of Rotarix in the US born infants. Hence this research addresses these limitations by quantifying the incidence and cost of Rotavirus (RV) and Acute Gastroenteritis (AGE) among children less than 5 years of age among commercial and Medicaid plans. Additionally the study also assessed the impact of incomplete and complete vaccination among those in commercial and Medicaid plans. Study population included beneficiaries who continuously received benefits for at least 6 months while aged <5 years were identified separately in commercial (2000-2010) and Medicaid (2002-2009) claims. Incidence of RV-coded encounters, diarrhea-coded but RV-attributable encounters, and first RV episodes were calculated, along with incremental cost of first RV episodes. Incidence rates among the post vaccination period reduced significantly compared to pre vaccination period for both RV coded and diarrhea coded, but RV attributable disease in both population. Incremental per-patient per-month cost of first RV episodes in Medicaid was $2,054 and $3608 in commercial. Forty two percent of children in the commercial population had completed vaccination by 2010, and 11.1% of Medicaid patient had completed vaccination by 2009. Both complete and incomplete vaccination confers protection against RV episodes among inpatient visits, outpatient visits and ER visits for both population. Additionally there is evidence of strong indirect protection among those unvaccinated groups.