Comparative study of the safety and protective value, in pre-exposure use, of rabies vaccine cultivated on human diploid cells (HDCV) and of the new vaccine grown on Vero cells.

The object of the study is to compare the tolerance and the efficacy of a new inactivated rabies vaccine grown on Vero cells (PVRV), with the vaccine cultivated on human diploid cells (HDCV), using the schedule recommended by WHO for pre-exposure on days 0, 7 and 21. Of students exposed to a risk of rabies at Alfort Veterinary School, 144 volunteers received either HDCV or PVRV vaccine. No student received a booster between the first blood sample before immunization on day 0 and the last antibody titration 21 months after the beginning of immunization. No serious side-effect occurred with either vaccine, although some vaccinees complained of redness, induration or local pain and, exceptionally, of fever. The study indicates the excellent immunogenicity of both HDCV and PVRV vaccines in all vaccinees. The geometric mean of antibody titres shows a higher titre in the PVRV group and a rapid decline in immune response with both vaccines, four months after the first injection, followed by a stabilization of the antibody level throughout the rest of the study. It should be noted, however, that very few individuals were found to be seronegative 21 months after the first injection.