Phase 1 study of an inactivated vaccine against American tegumentary leishmaniasis in normal volunteers in Brazil

A Phase 1 double-blind placebo-controlled study was performed to evaluate a vaccine against American tegumentary leishmaniasis in 61 healthy male volunteers. Side effects and the immune response to the vaccine were evaluated, with 1- and 2-dose schemes, with intervals of 7 or 21 days, each dose containing 1440 mg of protein N antigen of a single strain of Leishmania amazonesis (PH8) diluted in merthiolated saline (1:10,000). Merthiolated saline and an inert substance were used to placebos. No significant clinical alterations were found following the respective injections in the vaccinated individuals as compared to the placebos, except for local pain, which was associated significantly with injection of the vaccine. The laboratory alterations were observed bore no association with the clinical findings and were unimportant. We observed no differences between the groups with regard to seroconversion or the Montenegro skin test. However, the group that received a single dose of the vaccine and the one that received two doses with a 21-day interval displayed cutaneous induration significantly larger than in the control group, with 100%, 100%, and 66% conversion in the skin test, respectively. We concluded that the vaccine dose not present any major side effect that would contraindicate its use in healthy individuals.