title: Safety, Immunogenicity, and Protective Efficacy of the Whole-Cell/Recombinant B Subunit (WC/rBS) Oral Cholera Vaccine Against Travelers' Diarrhea.
abstract: Background: A prospective, randomized, double-blind, placebo-controlled trial of WC/rBS oral cholera vaccine was conducted in 502 U.S. college students attending summer educational programs in Mexico. Methods: Two doses of vaccine (or placebo) were administered 10 days apart immediately after arrival in Mexico. Results: The vaccine was free of significant adverse side effects. Anticholera toxin seroconversion was demonstrated in 86.7% of vaccinees compared to 8.2% of controls (p <.001). Postvaccination titers varied according to disease status (travelers' diarrhea) and enteropathogen isolated when disease developed. Protective efficacy (PE) against enterotoxigenic Escherichia coli (ETEC) diarrhea was 50% (95% CI, 14-71%), beginning 7 days after the second dose of WC/rBS. However, 74% of ETEC cases occurred within 7 days of the second dose, when no efficacy was demonstrated. Conclusions: Vaccines employed to prevent travelers' diarrhea will likely need to be administered before arrival in a developing country to be predictably beneficial. An unexpected finding was that infection with LT-ETEC after primary oral cholera immunization appears to augment the antitoxin response to WC/rBS vaccine. (J Travel Med 2:22-27, 1995)
authors.affiliation: Center for Infectious Diseases, University of Texas School of Public Health, Houston.
authors.initials: EG
authors.lastname: Scerpella
authors.initials: JL
authors.lastname: Sanchez
authors.initials: III
authors.lastname: Mathewson
authors.initials: JV
authors.lastname: Torres-Cordero
authors.initials: JC
authors.lastname: Sadoff
authors.initials: AM
authors.lastname: Svennerholm
authors.initials: HL
authors.lastname: DuPont
authors.initials: DN
authors.lastname: Taylor
authors.initials: CD
authors.lastname: Ericsson