Safety, tolerability, and immunogenicity of zoster vaccine in subjects with a history of herpes zoster

Background: Prior clinical studies of zoster vaccine enrolled subjects without a history of herpes zoster (HZ), so there are limited data on safety and immunogenicity in vaccinees with a prior history of HZ. This study was conducted to evaluate the safety and immunogenicity of zoster vaccine recipients who had a prior episode of HZ.

Methods: A total of 101 subjects > or = 50 years of age with a prior history of HZ were enrolled. They were stratified by number of years since their HZ (5 to 9 years and > or = 10 years, in an approximate 2:1 ratio), and randomized 1:1 to one of two vaccination groups. On day 1, Group I was administered zoster vaccine and Group II received placebo. At week 4, Group I received placebo and Group II received zoster vaccine. Subjects were followed for adverse experiences (AEs), exposure to varicella or HZ, and development of any varicella/varicella-like or HZ/HZ-like rashes, for 28 days after each injection. Blood samples were obtained prior to study injection on day 1 and week 4, and at week 8. Serum was assessed for varicella-zoster virus (VZV) antibody concentration by glycoprotein enzyme-linked immunosorbent assay.

Results: No serious AEs were reported within the 28-day safety follow-up period following any vaccination. Although a higher percentage of subjects reported injection-site AEs after receiving zoster vaccine than did placebo recipients, the proportion of subjects reporting systemic clinical AEs was similar in both groups. Zoster vaccine induced a VZV antibody response at 4 weeks post-vaccination. The estimated geometric mean titer (GMT) ratio (vaccine/placebo) was 2.07 (95% CI: 1.48, 2.88). The geometric mean fold-rise (GMFR) from prevaccination to week 4 post-vaccination was 2.1 in zoster vaccine recipients, versus 1.0 in placebo recipients.

Conclusions: In HZ history-positive adults > or = 50 years of age, zoster vaccine: (1) was well tolerated; and (2) significantly boosted the level of VZV antibody from baseline to 4 weeks post-vaccination as measured by GMT and GMFR. These data support the Advisory Committee on Immunization Practices' recommendation for routine zoster vaccination for all immunocompetent persons >/=60 years of age irrespective of HZ history.