Safety and immunogenicity of the recombinant zoster vaccine (LZ901) against herpes zoster in Chinese old people: A phase I trial

Despite ongoing efforts to reduce the burden of herpes zoster (HZ), it remains a global health concern. This partly-blinded, randomised controlled, dose-escalation phase I trial (CTR20220088) assessed the safety and immunogenicity of LZ901, an alum-adjuvanted recombinant zoster vaccine developed locally in China. Between Jan 15 and Oct 31, 2022, 80 healthy adults aged 50–70 years without prior varicella/HZ infection or varicella vaccination were equally randomised to receive LZ901 (50μg or 100μg), placebo, or a positive-controlled (HZ/su, Shingrix®). The primary outcome was safety, evaluated by adverse events (AEs) within 30 days after each vaccination and serious adverse events (SAEs) from first vaccination to six months post-vaccination. Exploratory outcomes included immunogenicity, assessed via anti-gE antibody and anti-VZV IgG concentrations, and gE-specific CD4+ and CD8+ T-cell responses. Within 30 days post-full vaccination, the overall incidence of AEs was 55.00% in both LZ901 dose-level groups, lower than that in the positive-controlled group (100.00%); no vaccine-related SAEs were reported. The geometric mean fold-rise of anti-gE antibody was 34.04 (50μg) and 16.88 (100μg), versus 118.99 (positive-controlled) and 1.08 (placebo). CD4+ T-cell responses were observed in 85.00% (50μg) and 95.00% (100μg) of LZ901 recipients, compared with 80.00% in the positive-controlled group. These findings indicated that LZ901 is safe, well tolerated, and immunogenic in older adults, supporting further evaluation of the safety profile and efficacy of LZ901 as a zoster vaccine candidate.