Background. GSK Vaccines' investigational herpes zoster (HZ) subunit vaccine (HZ/su) containing varicella-zoster virus glycoprotein E (gE; 50 µg) and the AS01B adjuvant system demonstrated 97.2% efficacy in reducing the risk of HZ in older adults (≥50 years of age) (Lal et al, NEJM 2015). Although the duration of protection is currently unknown, persistence of the immune response following 2-dose vaccination with HZ/su in healthy older adults was observed for up to 6 years post-dose 1 in a separate study (Lal et al, IDWeek 2014). Here, 3 statistical models were used to predict whether the immune response to vaccination with HZ/su persists beyond 6 years. Methods. Vaccine-induced immune response data from healthy older adults (≥60 years of age) who had received 2 doses (2 months apart) of HZ/su in a previous trial conducted in the Czech Republic, Germany, Sweden and the Netherlands were recorded for up to 6 years post-dose 1 (NCT00434577 and NCT01295320). To predict the persistence of the immune responses beyond the 6 years observed in the clinical trial, frequencies of gE-antigen-specific CD4+ T cells and serum anti-gE antibody concentrations from subjects who received 2 doses of HZ/su, were used to fit the piece-wise, power-law, and Fraser models. Results. Six years post-dose 1, both cell-mediated and humoral immune responses were above baseline values (figure 1). All 3 models predicted that both the cell-mediated and the humoral immune responses will persist (remain above the baseline values) beyond 6 years post-dose 1 (figure 2). Irrespective of the model, for up to 10 years post-dose 1, at least a 2.4-fold increase was seen for the cell-mediated immune response and at least a 4.5-fold increase was seen for the humoral immune response compared to baseline values (figure 3). Conclusion. Modeling the immune response persistence based on the 6-year data predicts that vaccine-induced immune responses in healthy older adults will remain above baseline values for at least 10 years after 2-dose vaccination with HZ/su. Funding. GlaxoSmithKline Biologicals SA Disclosures. H. Lal, GSK group of companies: Employee and Shareholder, Salary; R. Chlibek, GSK group of companies: Investigator, Research support. Pfizer: Speaker's Bureau, Speaker honorarium. Gilead: Investigator, Research grant; K. Pauksens, GSK group of companies: Investigator, Research support; T. F. Schwarz, GSK group of companies: Speaker's Bureau, Speaker honorarium; J. H. Richardus, GSK group of companies: Grant Investigator, Research support; T. C. Heineman, GSK group of companies: Employee, Salary; G. Catteau, GSK group of companies: Employee, Salary
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Lal et al. (2015) studied this question.