The endpoints of the out-patient, dose-ranging Phase II study were to determine the optimal dose of Ty800 for further development based on the safety, reactogenicity, and immunogenicity of the vaccine.
Data from the trial showed that the single-dose, oral vaccine was well tolerated and immunogenic, demonstrating that the desired immune response was achieved. Incidence of reactogenicity symptoms and adverse events post-vaccination were similar to placebo. Importantly, immunogenic response was dose-dependent. Positive immune response or seroconversion (prospectively defined as a four-fold increase in anti-LPS titers over pre-dose level) rates were 65.5% (36/55) and 80% (44/55) in the low and high dose groups, respectively, and was significantly (p<0.001) higher than placebo. Una Ryan, president and CEO of Avant, said: "The Ty800 data indicate that company's vaccine may have significant potential advantages over currently licensed vaccines, in term of safety, protectivity and ease of administration."