A New Leptospiral Vaccine for Use in Man. II. Clinical and Serologic Evaluation of a Field Trial with Volunteers

Abstract

A double-blind field trial for clinical and serologic evaluation of a new leptospiral vaccine was performed. The new vaccine, consisting of killed Leptospira, the only one grown in a chemically defined medium, was innocuous, and led to seroconversion in 57% of all volunteers who received two doses of the vaccine. The vaccine had a booster effect in 100% of volunteers with previous records of clinical leptospirosis. The new vaccine, named Shen-Tor, was approved by the Israeli Ministry of Health for vaccination of 700 irrigation workers in a trial designed to measure the potency of the vaccine to protect against leptospirosis in a natural setting.