(P-239) Yellow Fever Vaccine Usage in Three United States Healthcare Databases and Risk of Neurotropic Disease and Viscerotropic Disease in Vaccinees

Background: Yellow fever (YF) vaccination is contraindicated in individuals with immunosuppression who are at increased risk for rare serious adverse events, such as YF vaccine-associated neurotropic disease (YEL-AND) and YF vaccine-associated viscerotropic disease (YEL-AVD).

Objectives: To describe YF vaccine usages, the proportion of YF vaccinees with medical conditions causing immunosuppression and to estimate the risk of neurotropic disease and viscerotropic disease after vaccination using three US healthcare databases.

Methods: A descriptive analysis was conducted separately within Optum® de-identified Electronic Health Record (EHR) dataset (2007-2019) and two administrative claims datasets, Optum's De-identified Clinformatics Data Mart (CDM) (2004-2019) and IBM® MarketScan® (2007-2019). All YF vaccinees were retrieved during the study period, and their demographics and medical histories were described. Incident neurotropic and viscerotropic events, without likely alternative etiologies, were identified within 30-days post vaccination based on knowledge of YEL-AND and YEL-AVD. Reporting rates per 100,000 vaccinees with 95% confidence intervals (CI) were calculated among those with ≥ 183-days continuous medical coverage before vaccination and ≥ 30-days follow-up post vaccination. All analyses were stratified by vaccine brand (YF-Vax® or Stamaril®).

Results: A total of 92,205 (YF-Vax:77,278; Stamaril: 14,927), 46,539 (YF-Vax: 41,683; Stamaril: 4,856) and 125,235 (YF-Vax: 109,931; Stamaril: 15,304) YF vaccinees were retrieved in Optum EHR, Optum CDM and IBM MarketScan databases, respectively. The peak age of vaccinees was 18-29 years, followed by 50-59 years. Few vaccinees had thymic disorders (≤0.02%), autoimmune diseases (≤0.1%) or cancer ( <1%). The findings were similar when stratified by YF-Vax and Stamaril. The reporting rates of neurotropic disease were 1.41 (95% CI 0.15, 6.61) and 3.04 (95% CI 0.86, 8.11) per 100,000 vaccinees in Optum EHR and IBM MarketScan, respectively, with no events in Optum CDM. Three neurotropic events occurred after receipt of YF-Vax, while one event occurred following receipt of Stamaril. No viscerotropic events were identified in any database.

Conclusions: The majority of vaccinees likely represent those with ability to travel for leisure to YF endemic countries. The proportion of vaccinees with medical conditions causing immunosuppression were small, providing evidence that vaccination guidelines are well adhered to. The risk of developing neurotropic disease and viscerotropic disease remain low, providing further support for the safety of YF vaccines.