Effectiveness of the glycoprotein E (gE)-based adjuvanted recombinant zoster vaccine (RZV) lasts at least 7 years postvaccination, according to an ongoing follow-up study.

The research, published in Clinical Infectious Diseases, evaluated persistence of efficacy and immune responses for 6 additional years in adults vaccinated with RSV in two pivotal efficacy trials (ZOE-50/70).

The recent interim analysis involving participants aged 50 years and older was performed after more than 2 additional years of follow-up, between 5.1 and 7.1 years (mean) postvaccination, and includes partial data for year 8 postvaccination, according to the study team.

The article points out that annual assessments were performed for efficacy against herpes zoster (HZ) from Year 6 postvaccination onwards, and for anti-gE antibody concentrations and gE specific CD4[2+] T-cell (expressing more than two of four assessed activation markers) frequencies from Year 5 postvaccination onwards.

With 7,413 participants enrolled for the long-term efficacy assessment, most, 7,277 with mean age at vaccination of 67.2 years, were included in the cohorts for the evaluation of efficacy, 813 for the evaluation of humoral immune responses, and 108 for evaluation of cell-mediated immune responses.

Results indicated that efficacy of RZV against HZ through this interim analysis was 84.0% (95% confidence interval [CI], 75.9-89.8) from the start of the 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,” the researchers point out. “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.”

The study concluded, “Efficacy 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.”

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