[Challenge clinical trial for evaluation of a vaccine candidate strain against cholera].

INTRODUCTION

live attenuated oral Vibrio cholerae Ol El Tor, Ogawa strain 638 has demonstrated to be well tolerated and immunogenic when administrated orally in studies carried out in healthy volunteers.

OBJECTIVES

to evaluate the protection against cholera infection in a challenge clinical trial, for the technological and pharmaceutical scale-up of this vaccinal candidate as active ingredient at industrial level.

METHODS

a total of 21 healthy volunteers were involved in this trial; the vaccine candidate was administered to 12 of them and the remaining nine were given the placebo. Twenty eight days later, all of them received an infective dose of a V. cholerae virulent strain.

RESULTS

diarrheas were observed in 7 out of 9 placebos whereas not a single vaccinated volunteer showed diarrheas. More frequent and intense loose stools were found in the placebo volunteers with O-blood group. All volunteers in he placebo group excreted V. cholerae, but only three (25%) out of the 12 vaccinated volunteers did so.

CONCLUSION

in this challenge clinical trial model, the 638 strain proved to protect people against the diarrhea caused by a virulent V. cholerae strain.