Diarrheal disease is a significant cause of morbidity and mortality worldwide; it is the second leading cause of death in children under the age of 5, with approximately 800,000 deaths annually. Both Shigella and ETEC are common causes of traveler’s diarrhea and global children’s diarrhea.

This research is a phase 1, double-blind, placebo-controlled, dose-escalating, single-center study, involving three vaccine dosage escalation cohorts (108, 109, and 1010 cfu vaccine organisms) evaluating a combined Shigella and ETEC vaccine.

Each of the three dose-escalation cohorts will consist of 8 study participants who will be randomly allocated to receive either vaccine or placebo, as a single, oral dose.

A fourth cohort will be an adaptive design cohort consisting of 30 study participants to be randomly allocated to receive either two doses of vaccine, one dose of vaccine, or two doses of placebo. Participants in the first three cohorts will receive the oral dose while in an 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.