Randomized, double-blind placebo-controlled trial to evaluate the safety and immunogenicity of combined Salmonella typhi Ty21a and Vibrio cholerae CVD 103-HgR live oral vaccines

Healthy adults (n = 330) were randomized to receive either a bivalent vaccine composed of Vibrio cholerae CVD 103-HgR and Salmonella typhi Ty21a or a placebo. The combined vaccine was well tolerated. Approximately 80% of vaccinees manifested a significant rise in anti-S. typhi immunoglobulin G or immunoglobulin A lipopolysaccharide antibody levels. Significant (fourfold or greater) rises in anti-Inab,a or anti-Ogawa vibrio-cidal antibody titer were achieved by 91 and 80% of vaccine recipients, respectively. Elevated baseline vibrio-cidal antibody titers showed a modest suppressive effect on the rate of seroconversion.