Rotavirus vaccination in a Medicaid infant population from four US states: compliance, vaccination completion rate, and predictors of compliance

A retrospective observational cohort study was conducted using Medicaid administrative claims data from four states in the United States (US) to analyze overall and state-specific compliance and completion rates for rotavirus (RV) vaccines. Compliance was based on an infant receiving the recommended number of doses each within the appropriate time frame, and completion was based on an infant receiving the recommended number of doses over a recommended time period. Compliance and completion were defined separately for RV vaccines by package insert (PI) and Advisory Committee on Immunization Practices (ACIP) guidelines. Infants born between 1 May 2008 and 31 October 2011 in Florida, 31 July 2012 in Iowa and Kansas, and 30 April 2013 in Mississippi, and continuously enrolled in Medicaid with medical and pharmacy benefits for >= 8 months from birth were included. Study participants were assigned to cohorts based on type of RV vaccinations received within recommended vaccination windows. Using the PI guidelines, there were 658,219 eligible infants; 40% received no RV vaccines. The RV1 cohort had a significantly higher proportion of compliant infants compared to the RV5 cohort (54% vs. 25%; p<0.001). For infants initiating RV1, 55% completed both doses; for infants initiating RV5, 44% completed all three doses (p<0.001). Analysis by state and by ACIP guidelines yielded similar trends. Major predictors of compliance to RV vaccination were use of RV1 vaccine and DTaP vaccination completion. Increased awareness to the importance and timeliness of vaccination is needed.