Abstract / Summary
Background: Evidence on the real-world use of the MAV/06-strain live attenuated varicella vaccine (BARYCELA inj.) in adolescents and adults is limited. We described postvaccination ELISA seropositivity and recorded medically attended events in recipients aged ≥ 13 years. Methods: This retrospective cohort study included recipients vaccinated at a tertiary academic medical center in South Korea. Serologic analyses included selected participants documented as VZV IgG-negative at baseline who subsequently underwent postvaccination testing during routine care; dose scheduling and testing were individualized according to prior vaccination documentation and clinical need. Hospital encounters within 42 days after vaccination and institution-associated reports in the national adverse-event reporting system were reviewed. Results: Of 1715 administered doses, 988 patients aged ≥ 13 years received 1295 doses and comprised the safety cohort. The serology cohort included 199 participants and 202 dose-specific assessments. ELISA seropositivity was observed in 80/98 participants (81.6%; 95% CI, 72.8–88.1%) in the post-dose 1 cohort and 90/104 (86.5%; 95% CI, 78.7–91.8%) in the post-dose 2 cohort. Nine medically attended events were identified within 42 days (0.69% per administered dose; 95% CI, 0.32–1.32%), of which one mild fever episode was considered possibly related to vaccination. Substantial postvaccination ELISA seropositivity was observed in this selected cohort of adolescents and adults. Few medically attended events were identified in the available institutional records and national adverse-event reports, and one mild fever episode was considered possibly related to vaccination. Prospective studies with paired, protocol-timed sampling and cellular immune assessments are needed.