Several technological hurdles impede the large-scale manufacturing of a human diploid cell (HDC) vaccine (HDCV) for rabies. Kanghua Biological Products Co., Ltd. developed a lyophilized and purified HDCV using microcarrier technology for large-scale growth of HDCs in bioreactors. Researchers evaluated the safety and immunogenicity of this vaccine in a healthy population immunized according to the Essen post-exposure vaccination schedule in this blinded, randomized, parallel-group research conducted between July and October 2014 in Mianzhu, Sichuan Province, China. As a control, a hamster kidney cell vaccination was utilized. To determine safety, adverse responses were observed at 0.5, 6, 24, 48, and 72 hours after immunization. Neutralizing antibodies in venous blood were evaluated on days 7, 14, and 72 to assess the vaccine’s immunogenicity, with 1 month of follow-up monitoring. The frequencies of systemic and local adverse responses were 10.6 percent and 2.9 percent in the test group, respectively, and 20.0 percent and 13.6 percent in the control group. The positive conversion rates of antibodies in the test and control groups were 100 percent and 98.82 percent, respectively, after the third injection.

Furthermore, the average antibody titers on days 7, 14, and 42 were 1.71, 2.72, and 1.29 times greater than those in the control group, respectively. These findings suggest that HDCV had greater immunogenicity and a better safety profile than the hamster kidney cell rabies vaccine.