Efficacy of an adjuvanted herpes zoster subunit vaccine in older adults.
Level 2 - randomized trial
Individual randomized, placebo-controlled trial
PubMed 25916341 · doi:10.1056/NEJMoa1501184
What was done
A phase 3 randomized, placebo-controlled trial across 18 countries evaluated the efficacy and safety of the HZ/su vaccine (varicella-zoster virus glycoprotein E with AS01B adjuvant) in adults aged 50 years or older. Participants were stratified by age (50–59, 60–69, and ≥70 years) and randomized to receive two intramuscular doses of vaccine or placebo 2 months apart. The primary outcome was vaccine efficacy in reducing confirmed herpes zoster cases over a mean follow-up of 3.2 years.
What was found
Among 15,411 evaluable participants (7,698 vaccine, 7,713 placebo), herpes zoster was confirmed in 6 participants in the vaccine group and 210 in the placebo group (incidence rate: 0.3 vs. 9.1 per 1,000 person-years). Overall vaccine efficacy against herpes zoster was 97.2% (95% CI, 93.7 to 99.0; P < 0.001), ranging from 96.6% to 97.9% across all age strata. Grade 3 solicited or unsolicited symptoms within 7 days were reported in 17.0% of vaccine recipients and 3.2% of placebo recipients, while rates of serious adverse events, potential immune-mediated diseases, and deaths were similar between groups.
Why it matters
This trial establishes that the adjuvanted HZ/su subunit vaccine provides very high protection (>96%) against herpes zoster in older adults, critically maintaining efficacy even in those aged 70 years and older.
Limits
The mean follow-up of 3.2 years leaves longer-term persistence of protection unassessed in this report. The vaccine caused substantially higher short-term reactogenicity, with grade 3 symptoms occurring in 17% of recipients compared with 3.2% in the placebo arm.