Objective: An effective vaccine to prevent SA is needed. V710, a vaccine containing a SA-surface protein (IsdB), has demonstrated protection in preclinical models. A Phase I, dose-ranging study was conducted to assess immunogenicity and safety of an adjuvanted, liquid formulation of V710.
Methods: This multicenter, double-blind study randomized 124 adults (18-55 years) to receive a single 0.5-mL intramuscular vaccination with V710 (5, 30, or 90 µg) or saline placebo (in 1:1:1:1 fashion). Blood samples were collected at screening and Day 3 (D3), D7, D10, D14, D28, D56, and D84 postvaccination. Sera were analyzed for IsdB-specific antibodies using a total IgG assay. The primary immunogenicity time-point was D14. Safety was assessed for 14 days postvaccination.
Results: By D14, a greater proportion of subjects manifested a positive immune response (defined as >2-fold increases in antibody levels) in the V710 30-mg [86% (95% CI 67%, 96%)] and V710 90-mg [85% (66%, 94%)] groups, relative to V710 5-mg [29% (14%, 48%)] or placebo [4% (0.1%, 18%)] groups. Likewise, by D14, higher geometric mean concentrations were achieved in V710 30-mg [119 µg/mL (95% CI 91, 157)] and 90-mg [151 µg/mL (108, 212)] groups, relative to V710 5-mg [51 µg/mL (39, 66)] or placebo [23 µg/mL (16, 34)] groups. Responses were noted by D10 and persisted through D84. No SAE, fever, or significant laboratory abnormalities were reported. The most common vaccine-related AEs were injection-site pain, nausea, fatigue, and headache.
Conclusions: V710 was immunogenic at D14 following single vaccination. V710 was generally well tolerated at all doses.