[Evaluation of the effectiveness of a new vaccine against human leptospirosis in groups at risk]. / Evaluación de la efectividad de una nueva vacuna contra la leptospirosis humana en grupos en riesgo.

In order to evaluate the effectiveness of a new vaccine against human leptospirosis, a prospective cohort study was done with persons in the Cuban province of Holguín who were at risk of becoming ill with leptospirosis. The study included 118,018 persons from 15 to 65 years old who were considered to face either permanent or temporary risk. The vaccinated cohort consisted of 101,137 persons. They received two vaccine doses, 6 weeks apart, of 0.50 mL via deep intramuscular injection into the deltoid muscle of the nondominant arm. The unvaccinated cohort consisted of 16,881 persons. Epidemiological surveillance began 21 days after the application of the second vaccine dose and continued for 1 year. The same criteria for suspected and confirmed cases were maintained throughout the study period. At the end of the surveillance period effectiveness was calculated as being higher than 97%. It is estimated that the vaccination program prevented eight out of ten cases that would have otherwise occurred. Vaccine reactogenicity was also measured in a subsample of 1,500 persons between 15 and 65 years old. The observed symptomatology was low. Slight pain at the injection site was the most frequent symptom (25%). The results of the study indicate the usefulness of the vaccine for disease prevention among people at risk, and its use is thus recommended.

[The reactogenicity and immunogenicity of the first Cuban vaccine against human leptospirosis]. / Reactogenicidad e inmunogenicidad de la primera vacuna cubana contra la leptospirosis humana.

A controlled double-blind trial was conducted with the participation of 80 adult volunteers of both sexes, who were randomly divided into groups of 40 individuals each one. The case-base study received the vaccine and the control group was administered placebo to know the safety, the behaviour of reactogenicity, and to star the immunogenicity studies of the first Cuban vaccine against human leptospirosis. The vaccine used in the case-base study was an inactivated and trivalent vaccine containing strains of Leptospira canicola, icterohaemorrhagiae and pomona, since they have the highest circulation in the country. The results obtained showed the inocuity of the vaccine as no adverse severe reactions were detected. The general symptomatology observed was low, where as febricula was the most common general symptom. It appeared during the first 3 days of observation and there were no significant differences between the 2 group. Only a mild pain at the site of the injection was reported as a local symptom, which was more frequent in the vaccinated group than in the control group (7.8 against 1.5%, respectively). The seroconversion obtained was of 29% by microagglutination, and of 34.2% by ELISA. The final results allowed to conclude that this vaccine is safe for human adults at the ages under study, and give the possibility to continue other studies in more advanced stages to complete the requirements for obtaining its license.