The Adjuvanted Recombinant Zoster Vaccine Confers Long-term Protection Against Herpes Zoster: Interim Results of an Extension Study of the Pivotal Phase III Clinical Trials (ZOE-50 and ZOE-70).

Abstract

BACKGROUND\nThis is an ongoing follow-up study (NCT02723773) evaluating persistence of efficacy and immune responses for six additional years in adults vaccinated with the glycoprotein E (gE)-based adjuvanted recombinant zoster vaccine (RZV) at ≥50 years of age in two pivotal efficacy trials (ZOE-50/70). The present interim analysis was performed after ≥2 additional years of follow-up (between 5.1 and 7.1 years [mean] post-vaccination) and includes partial data for year (Y)8 post-vaccination.\n\n\nMETHODS\nAnnual assessments were performed for efficacy against herpes zoster (HZ) from Y6 post-vaccination onwards, and for anti-gE antibody concentrations and gE-specific CD4[2+] T-cell (expressing ≥2 of four assessed activation markers) frequencies from Y5 post-vaccination onwards.\n\n\nRESULTS\nOf 7413 participants enrolled for the long-term efficacy assessment, 7277 (mean age at vaccination: 67.2 years), 813, and 108 were included in the cohorts for the evaluation of efficacy, humoral immune responses, and cell-mediated immune responses, respectively. Efficacy of RZV against HZ through this interim analysis was 84.0% (95% confidence interval [CI]: 75.9-89.8) from the start of this follow-up study and 90.9% (95%CI: 88.2-93.2) from vaccination in ZOE-50/70. Annual vaccine efficacy estimates were >84% for each year since vaccination and remained stable during this follow-up study through the interim analysis. Anti-gE antibody geometric mean concentrations and median frequencies of gE-specific CD4[2+] T cells had plateaued throughout this follow-up study up to the interim analysis, at ~6-fold above pre-vaccination levels.\n\n\nCONCLUSION\nEfficacy against HZ and immune responses to RZV remained high, suggesting that the clinical benefit of RZV in older adults is sustained for at least seven years post-vaccination.