A phase 3 clinical trial evaluated the efficacy and safety of an adjuvanted herpes zoster subunit vaccine (HZ/su) in older adults aged 50 years or older. The vaccine, containing varicella-zoster virus glycoprotein E and the AS01B adjuvant system, was compared with a placebo. A total of 15,411 participants were enrolled, with 7,698 receiving the vaccine and 7,713 receiving placebo. The study followed participants for a mean of 3.2 years, during which 6 cases of herpes zoster were confirmed in the vaccine group and 210 in the placebo group, resulting in an overall vaccine efficacy of 97.2% (95% CI, 93.7 to 99.0). Vaccine efficacy was consistent across all age groups (50-59, 60-69, and ≥70 years). The vaccine was well tolerated, with more frequent solicited injection-site and systemic reactions in the vaccine group. Grade 3 symptoms were reported in 17.0% of vaccine recipients and 3.2% of placebo recipients. Serious adverse events and potential immune-mediated diseases were similar in both groups. The study found no significant safety concerns, and the vaccine was effective in reducing the risk of herpes zoster in adults 50 years or older, with similar efficacy in those 70 years or older. The HZ/su vaccine showed greater reactogenicity than placebo, with injection-site and systemic reactions being more common. The vaccine's efficacy was maintained even in the oldest age group, suggesting it can overcome immunosenescence. The study concluded that HZ/su significantly reduced the risk of herpes zoster in older adults, with overall efficacy well preserved in those 70 years or older. The vaccine is supported by GlaxoSmithKline Biologicals.A phase 3 clinical trial evaluated the efficacy and safety of an adjuvanted herpes zoster subunit vaccine (HZ/su) in older adults aged 50 years or older. The vaccine, containing varicella-zoster virus glycoprotein E and the AS01B adjuvant system, was compared with a placebo. A total of 15,411 participants were enrolled, with 7,698 receiving the vaccine and 7,713 receiving placebo. The study followed participants for a mean of 3.2 years, during which 6 cases of herpes zoster were confirmed in the vaccine group and 210 in the placebo group, resulting in an overall vaccine efficacy of 97.2% (95% CI, 93.7 to 99.0). Vaccine efficacy was consistent across all age groups (50-59, 60-69, and ≥70 years). The vaccine was well tolerated, with more frequent solicited injection-site and systemic reactions in the vaccine group. Grade 3 symptoms were reported in 17.0% of vaccine recipients and 3.2% of placebo recipients. Serious adverse events and potential immune-mediated diseases were similar in both groups. The study found no significant safety concerns, and the vaccine was effective in reducing the risk of herpes zoster in adults 50 years or older, with similar efficacy in those 70 years or older. The HZ/su vaccine showed greater reactogenicity than placebo, with injection-site and systemic reactions being more common. The vaccine's efficacy was maintained even in the oldest age group, suggesting it can overcome immunosenescence. The study concluded that HZ/su significantly reduced the risk of herpes zoster in older adults, with overall efficacy well preserved in those 70 years or older. The vaccine is supported by GlaxoSmithKline Biologicals.