Immunogenicity Persistence of Different Immunization Regimens of Rabies Vaccine in the 10-60 Years Age Group: A Follow-Up Report Based on Phase III Clinical Trial.

Objectives: This study evaluated the 12-month persistence of rabies virus-neutralizing antibody (RVNA) following different immunization regimens of freeze-dried human rabies vaccine (Vero cells) in individuals aged 10-60 years within the Chinese population. Methods: Number of 600 participants from phase III clinical trials who completed the fullimmunization were randomly assigned into one of three groups, four-dose experimental group, five-dose experimental group, and five-dose control group. The experimental group received the vaccine from Shandong Yeedu Biotechnology Co., while the control group used the vaccine from Liaoning Chengda Biotechnology Co., Ltd. The antibody-positive rate and geometric mean concentration (GMC) were calculated, and analysis of variance was used to compare the results among the three groups. Results: The study included 200 participants in the four-dose experimental group, 186 in the five-dose experimental group, and 214 in the five-dose control group. Twelve months post-immunization, the overall RVNA-positive rates were 97.00%, 93.55%, and 94.86% in the four-dose experimental, five-dose control, and five-dose experimental groups, respectively. The GMCs of RVNA were 2.50, 2.05, and 2.04 IU/mL for the respective groups. The age-stratified analysis exhibited high positivity rates across age groups (≤21, 21-50, and ≥50), with rates ranging from 88.4% to 100%, and GMCs were between 1.75 and 2.61 IU/mL. Conclusions: Twelve months after full immunization, the overall RVNA-positive rate remained high across all dosing regimens, demonstrating satisfactory immunogenicity persistence. This indicates that both the four-dose and five-dose regimens are effective in maintaining long-term immunity against rabies.