title: Effectiveness of the WC/rBS oral cholera vaccine in the prevention of traveler's diarrhea: a prospective cohort study.
abstract: OBJECTIVE
  Traveler's diarrhea (TD) is the most frequent disease among people from industrialized countries who travel to less developed ones, especially sub-Saharan Africa, Southern Asia and South America. The most common bacteria causing TD is enterotoxigenic Escherichia coli (ETEC). The WC/rBS cholera vaccine (Dukoral) has been shown to induce cross-protection against ETEC by means of the B subunit of the cholera toxin. The aim of the study was to evaluate the effectiveness of the WC/rBS cholera vaccine in preventing TD.
  
  
  METHODS
  Between May 1 and September 30 (2007), people seeking pre-travel advice in ten Spanish international vaccination centers were included in a prospective cohort study of travelers to cholera risk countries. The incidence rates of TD were adjusted for variables whose frequencies were statistically different (entry point 0.10) between the vaccinated and non-vaccinated cohorts.
  
  
  RESULTS
  The vaccinated cohort (n = 544 travelers) included people vaccinated with the WC/rBS cholera vaccine, and the non-vaccinated cohort (n = 530 travelers) by people not vaccinated. The cumulative incidence rate of TD was 1.69 in vaccinated and 2.14 in non-vaccinated subjects. The adjusted relative risk of TD in vaccinated travelers was 0.72 (95% CI: 0.58-0.88) and the adjusted vaccination effectiveness was 28% (95% CI: 12-42).
  
  
  CONCLUSIONS
  The WC/rBS cholera vaccine prevents TD in 2 out of 7 travelers (preventive fraction: 28%). The number needed to vaccinate (NNV) to prevent 1 case of TD is 10.
authors: International Vaccination Center (IVC); Málaga, Spain.
authors: Rosa
authors: R
authors: López-Gigosos
authors: Magda
authors: M
authors: Campins
authors: María J
authors: MJ
authors: Calvo
authors: Santiago
authors: S
authors: Pérez-Hoyos
authors: Javier
authors: J
authors: Díez-Domingo
authors: Luis
authors: L
authors: Salleras
authors: María T
authors: MT
authors: Azuara
authors: Xavier
authors: X
authors: Martínez
authors: José M
authors: JM
authors: Bayas
authors: Josep M
authors: JM
authors: Ramón Torrell
authors: María A
authors: MA
authors: Pérez-Cobaleda
authors: María E
authors: ME
authors: Núñez-Torrón
authors: Lydia
authors: L
authors: Gorgojo
authors: Magdalena
authors: M
authors: García-Rodríguez
authors: Rosa
authors: R
authors: Díez-Díaz
authors: Luis
authors: L
authors: Armadans
authors: Concepción
authors: C
authors: Sánchez-Fernández
authors: Teresa
authors: T
authors: Mejías
authors: Cristina
authors: C
authors: Masuet
authors: Rafael
authors: R
authors: Pinilla
authors: Nieves
authors: N
authors: Antón
authors: Pilar
authors: P
authors: Segarra
mesh_terms: D000284:Administration, Oral; D000293:Adolescent; D000328:Adult; D022121:Cholera Vaccines / Q000008:administration & dosage* / Q000276:immunology*; D015331:Cohort Studies; D003967:Diarrhea / Q000453:epidemiology* / Q000517:prevention & control*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D013030:Spain; D014195:Travel; D016896:Treatment Outcome; D055815:Young Adult
chemical_list: D022121:Cholera Vaccines; C586175:Dukoral
keywords: Traveler's diarrhea; WC/rBS vaccine; cholera; effectiveness; number needed to vaccinate; preventive fraction