Efficacy of an Enterotoxigenic Escherichia coli (ETEC) Vaccine on the Incidence and Severity of Traveler’s Diarrhea (TD): Evaluation of Alternative Endpoints and a TD Severity Score

The efficacy of an Oral Whole Cell ETEC Vaccine (OEV) against Travelers’ Diarrhea (TD) was reexamined using novel outcome and immunologic measures. More specifically, a recently developed disease severity score alternative clinical endpoints were evaluated as part initial validation effort to access the vaccine intervention for first time in travelers endemic area. A randomized, double-blind, placebo-controlled trial followed Guatemala or Mexico up 28 days after arrival country following vaccination (two doses two weeks apart) with vaccine. Fecal samples collected upon arrival, departure, during TD pathogen identification. Serum subset subjects determine IgA cholera toxin B subunit (CTB) antibody titers their country. vaccine’s efficacy, utilizing other endpoints, including relationship between levels risk, assessed compared per-protocol primary endpoint. total 1435 completed 7–28 follow-up had available data. higher more severe (≥5 unformed stools/24 h) ETEC-attributable when accounting take (PE ≥ 50%; p < 0.05). protected less (3 4 symptom change activity = 76.3%, 0.01). Immunologic associated reduced risk infection enteric pathogens, lower severity. Clear observed among vaccinees ≥4 ≥5, regardless 72.0% 79.0%, respectively, ≤ 0.03). incidence ETEC, this warrants accelerated evaluation improved formulation (designated ETVAX), currently undergoing advanced field testing. Subjects serum CTB Campylobacter jejuni/coli. Furthermore, provided robust descriptor should be included endpoint future studies.