Immunogenicity and safety of a new Vero cell rabies vaccine produced using serum-free medium.

The immunogenicity and safety of a new human rabies vaccine, produced in Vero cells by a process that does not require supplementation with human or animal derived components in production, were assessed. Thus, the objective is to produce a safer vaccine at a lower cost. A total of 296 volunteers was divided into two groups: Group 1, which received the study vaccine, and Group 2, which received the Vero cells vaccine produced by Sanofi Pasteur. Five doses were given on days 0, 3, 7, 14 and 28. Blood samples for determination of rabies virus neutralizing antibodies were collected on days 0, 14, 38 and 90. The geometric mean titers (GMT) were much higher than 0.5 IU/ml in both groups on days 14, 38 and 90, indicating seroconversion according to the World Health Organization. In Group 1, however, the GMTs were higher than in Group 2, the difference being statistically significant in the two last samples. There was no statistical difference between the groups in the ratio of individuals with titers > or =0.5 IU/ml in each sample. Pain at the injection site was the most common adverse reaction and occurred most often in Group 1 (p < 0.001). All cases had a favorable evolution. There were no severe adverse reactions. It was concluded that the new vaccine is safe and immunogenic.