Citation:
Marshall H, Nissen M, Richmond P, Shakib S, Jiang Q, Cooper D, et al. Safety and immunogenicity of a booster dose of a 3-antigen Staphylococcus aureus vaccine (SA3Ag) in healthy adults: A randomized phase 1 study. Journal of Infection. 2016;73(5):437-54
Keywords:
Capsular polysaccharide conjugates; Clumping factor A; Functional antibodies; Staphylococcus aureus; Vaccine
Abstract:
Objective: A 2-stage, phase 1, randomized, placebo-controlled study in healthy adults to assess immunogenicity and safety of a booster dose at three dose levels of a 3-antigen Staphylococcus aureus vaccine (SA3Ag) containing recombinant clumping factor A (ClfA) and capsular polysaccharides 5 and 8 (CP5 and CP8) conjugated to a diphtheria toxoid.
Methods: Six months after initial single vaccination, in Stage 2, SA3Ag recipients were randomized (1:1) to booster vaccination or placebo, while Stage 1 placebo recipients received placebo again. Pre- and post-vaccination blood samples were analyzed.
Results: In Stage 2 (n = 345), pre-booster CP5 and CP8 titers remained high with no increase post-booster. ClfA titers remained high after initial vaccination and increased post-booster, approaching the peak response to the initial dose. Post-booster local reactions were more frequent and of greater severity than reported after the initial vaccination, particularly for the high-dose level recipients. Post hoc analysis showed no dose–response pattern and no obvious association between diphtheria toxoid titers and local reactions after initial or booster vaccination.
Conclusion: Immune responses after the initial vaccination persisted for the 12 months studied, with little additional response after the booster dose at 6 months. Post-booster injection site reactions were more frequent and more severe but self-limiting.