The purpose of this study is to determine whether a live, oral, combined Shigella-ETEC vaccine candidate, known as strain CVD 1208S-122, is safe and immunogenic. This will be a phase 1, double-blind, placebo-controlled, dose-escalating, single-center study, involving three vaccine dosage escalation cohorts (10^8, 10^9, and 10^10 cfu vaccine organisms). Each of the three dose-escalation cohorts will consist of 8 study participants who will be randomly allocated to receive either vaccine (n=6) or placebo (n=2), as a single, oral dose. An independent Safety Monitoring Committee (SMC) will review the available safety data for Cohorts 1 - 3 through 7 days post-vaccination before proceeding to the enrollment of the next cohort. The fourth cohort will be an adaptive design cohort consisting of 30 study participants to be randomly allocated to receive either two doses of vaccine (n=12), one dose of vaccine (n=12), or two doses of placebo (n=6), with the dosage selection based on the highest well-tolerated dose in the dose-escalation cohorts (1 - 3), as determined by the SMC.~Each of the dose-escalation cohorts (1 - 3) will receive the oral dose of blinded study product while in the inpatient setting. During the following subsequent 96 hours (4 days), participants will remain on the inpatient research isolation ward to be closely monitored, and each stool will be collected by study staff. The evaluation and monitoring of participants enrolled in the fourth cohort will be conducted entirely in the outpatient setting.
The purpose of this study is to determine whether a live, oral, combined Shigella-ETEC vaccine candidate, known as strain CVD 1208S-122, is safe and immunogenic.