A dynamic observation on the immune response to the freeze-dried without adjuvant Vero cell rabies vaccine

Objective The purpose of the present study was to evaluate the immunogenicity of the freeze-dried without adjuvant Vero cell rabies vaccine made in China. Methods A conventional vaccination procedure that included 5 injections of vaccine was applied to 90 patients who had exposed to rabies and were without history of rabies vaccination and dog bite injury,selected according to the requirements for recruitment and exclusion in the project. Blood samples were acquired before the first vaccination,7,14,28 and 45 days after the first vaccination and 180 days after the whole procedure of vaccination,respectively,for determination of anti-rabies neutralizing antibody. Results No anti-rabies neutralizing antibody was detected before the first vaccination in the subjects studied. The positive rate of anti-rabies neutralizing antibody was 12.22% 7 days after the first vaccination,and reached to 100% 14 days after the first vaccination which remained until 180 days after the whole procedure of the vaccination. Antibody geometric mean concentration (GMT) of anti-rabies neutralizing antibody was found to be 0.27 IU/ml 7 days after the first vaccination and raised to 2.52 IU/ml 14 days after the first vaccination,increasing by 9.33 folds compared to that found 7 days after the first vaccination,and to 4.43 and 7.08 IU/ml,respectively,28 and 45 days after the first vaccination,increasing by 1.76 and 2.81 folds,respectively,compared to that detected 14 days after the first vaccination. GMT of anti-rabies neutralizing antibody maintained at a high level (8.41 IU/ml) even 180 days after completion of the whole procedure of vaccination. Conclusion The freeze-dried without adjuvant Vero cell rabies vaccine made in China exhibited good immunogenicity. The people who have received vaccination within 6 months need not to be inoculated again when exposed to animals with rabies.