(334) Characterization of COVID-19 vaccine data in the Sentinel System

Background: COVID-19 vaccination has been delivered in a wide range of settings, from healthcare delivery visits to state sponsored vaccination fairs. Therefore, complete capture of vaccination status may benefit from using multiple code types, such as claims and CVX (vaccine administered) state-based Immunization Information Systems (CVX-IIS) codes, to enhance the ascertainment.

Objectives: To characterize the availability and code type of COVID-19 vaccine data in the Sentinel Distributed Database (SDD).

Methods: We identified individuals in 14 SDD Data Partners (DP), which included 12 commercial health plans, Medicaid, and Medicare, with evidence of at least one COVID-19 vaccine administration from November 2021 through February 2024. Demographic and clinical patient characteristics were identified 183 days before the first COVID-19 vaccine (index date). We characterized the index vaccination by vaccine brand (Pfizer, Moderna, Janssen, Novavax, or unspecified) and code type (NDC, CPT, HCPCS, or CVX-IIS). When applicable, the time between the first and second doses was calculated, and COVID-19 vaccines within 1-4 days of the index date were considered duplicates.

Results: Out of 14 DPs, 5 had linkage to IIS, but not all states provided IIS data for those 5 DPs. At the time of this analysis, at least one COVID-19 vaccination was captured for over 38 million members in the SDD; 55% were female, and 49% were aged ≥65 years, with a mean age of 57 years (standard deviation 16.4). The most prevalent health conditions among vaccinated enrollees were hypertension (27.3%), hyperlipidemia (22.5%), and obesity/overweight (18.8%). Of the first COVID-19 vaccine records, Pfizer accounted for 55.5%, Moderna for 40%, and Janssen, Novavax, or unspecified for 4.5%. The majority of index COVID-19 vaccines (79%) were identified by claim codes only, 9.5% were identified by CVX-IIS codes only, and 11.5% were identified by both code types. A small percentage ( < 1%) of members had evidence of duplicate data entry. The median time between the first and second COVID-19 vaccinations, excluding potential duplicates, was 29 days (interquartile range 21-33).

Conclusions: Data on more than 38 million COVID-19 vaccinees were available for analysis in the SDD at the time of this analysis. The quality of COVID-19 vaccine data in the SDD is high, with a low proportion of duplicate records. The median interval between the first and second COVID-19 vaccine doses is in line with the recommended intervals between the two most utilized vaccine brands. The Sentinel DPs continue to link to state-based IIS, and the number of vaccinees available for analysis is growing. Future planned analyses include characterizing individuals with primary vaccine series and booster doses.