Safety and tolerability of a high-potency zoster vaccine in adults ≥50 years of age

Abstract Background Herpes zoster (HZ) incidence rises with age, especially after 50 years of age, probably due to waning varicella-zoster virus (VZV)-specific immunity. The Shingles Prevention Study [Oxman MN, Levin MJ, Johnson GR, Schmader KE, Straus SE, Gelb LD, et al. A vaccine to prevent herpes zoster and postherpetic neuralgia in older adults, N Engl J Med 2005;352:2271–84], enrolled people ≥60 years of age and showed that zoster vaccine prevents HZ and postherpetic neuralgia (PHN), presumably through boosting VZV-specific immunity. This study of people ≥50 years of age compared the safety and tolerability of two zoster vaccine potencies. Methods Adults ≥50 years old enrolled in a randomized, double-blind, multicenter study to compare the safety and tolerability of one dose of two zoster vaccine potencies, ∼58,000 and ∼207,000 plaque-forming units/dose. Adverse experiences (AEs) were recorded on a standardized Vaccination Report Card for 42 days postvaccination. For assessment of injection-site AEs, clinically acceptable tolerability was predefined based on experience with PNEUMOVAX™ 23, a licensed vaccine recommended for use in older people. Results Six hundred and ninety-eight subjects (age 50–90 years, median 64 years) were enrolled. No serious vaccine-related AEs were reported. Similar AE rates were observed in the higher and lower potency groups (overall systemic AEs: 37.5 and 39.3%, vaccine-related systemic AEs: 10.9 and 13.2%, injection-site AEs: 63.0 and 59.8%). Rates for a combined endpoint of moderate or severe injection-site pain/tenderness/soreness and swelling were 17.2% (95% CI 13.9, 21.0) and 9.0% (95% CI 5.6, 13.4), respectively. Most combined endpoint events were reported as moderate in intensity. Conclusions Both vaccine potencies were generally well tolerated in this study of people ≥50 years of age. Although rates of some moderate or severe injection-site AEs were greater in the higher potency group, all rates met the prespecified criteria for clinically acceptable tolerability.