Recombinant Zoster Vaccine Confers Long-Term Protection in Older Adults

Approximately 10 years after receipt of an adjuvanted recombinant zoster vaccine, efficacy against herpes zoster infection and immune responses remained high. These study results were presented at IDWeek 2022, held from October 19 to 23, in Washington, DC.

Results of 2 phase 3 trials showed that an adjuvanted recombinant zoster vaccine had high protective efficacy against herpes zoster infection for up to 2 years among adults aged 50 years and older.

In this interim analysis, researchers evaluated patient data captured from year 4 of an extension study. The phase 3 trials were initiated in 2010 and completed in 2015, and the extension study was initiated in 2016; overall, the analysis comprised 10 years of data. The researchers assessed the efficacy of an adjuvanted recombinant zoster vaccine among adults aged 50 years and older who received the first vaccine dose in August 2010 and the second dose 2 months later. The persistence of vaccine-induced humoral immunity was evaluated up to August 2021.

The primary objective was to determine the efficacy of the vaccine against herpes zoster infection, which was determined using historical control estimates from patients included in the placebo groups of 2 previously conducted phase 3 parent trials.

A total of 7,277 adults were included in the efficacy analysis. Study participants were enrolled from 18 countries, and most were White or of European descent (76.0%). In addition, 60.7% of participants were women, and the mean age at enrollment ranged between 67.3 and 73.1 years.

Between 1 month following receipt of the second vaccine dose and year 4 of the extension study, the overall vaccine efficacy was 89.0% (95% CI, 85.6%-91.3%).

The mean concentration of anti-glycoprotein E (gE) antibodies remained more than 5 times higher than baseline (1320.5 mIU/mL) at years 5 (8053.5 mIU/mL), 6 (8512.5 mIU/mL), 7 (8398.2 mIU/mL), 8 (8221.2 mIU/mL), 9 (7209.1 mIU/mL), and 10 ( 6931.0 mIU/mL).

The frequency of gE-specific CD4²⁺ T cells increased between baseline (log₁₀, 89.8) and years 6 (log₁₀, 660.7), 7 (log₁₀, 581.5), 8 (log₁₀, 634.2), 9 (log₁₀, 800.6), and 10 (log₁₀, 684.4).

No additional safety signals were reported in this study.

According to the researchers, “Efficacy against HZ [herpes zoster] and immune responses to RZV [recombinant zoster vaccine] remained high until the end of the observation period.”

Disclosure: This study was supported by GlaxoSmithKline Biologicals SA, and multiple authors declared affiliations with industry. Please see the original reference for a full list of disclosures.