Coding Variations Hinder Vaccine Efficacy and Safety Research

Variation in Rotavirus Vaccination Coding in US State Medicaid Data

Layton JB, Butler AM, Brookhart MA, Panozzo CA


Valid real-world evidence depends on being able to accurately identify exposures of interest in real-world data. US Medicaid data could be a good option for research on the use, effectiveness, and safety of childhood vaccines due to the large number of US children enrolled in Medicaid. However, an analysis of rotavirus vaccination claims in 4 states’ Medicaid data revealed that states bill and record childhood vaccines very differently; the lack of granular billing codes and strong evidence of missing vaccine claims in some states’ data may make vaccine studies infeasible in those states. Finding that vaccine billing practices vary across states and over time, leads us to caution that researchers should carefully evaluate whether the data they need is accurately captured prior to beginning a study.

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