Abstract
To assess the factors that influencing the persistence of virus neutralizing antibody (VNA), and to establish prediction models to provide the appropriate timing for booster administration, a cohort of post-exposure rabies vaccine recipients was investigated. The VNA determined records from 2019 to 2023 and interrelated factors were analyzed, including gender, age, rabies immunoglobulin (RIG) administration, vaccine products, vaccination schedule, and vaccination intervals etc. The geometric mean of VNA titre within 1 month after primary vaccination with 2-1-1 schedule was statistically higher than that with 5-dose course (P = 0.031). The interaction between exposure and vaccination schedule was observed on primary vaccination, which showed that a decrease of 19.74 % (95 % CI: 5.99%-64.95 %, P = 0.008) of VNA titre among vaccinee with 5-dose and exposure III. Individuals with RIG administration produced lower VNA titres than those without RIG administration (P = 0.001). Vaccine products (Chengda, P = 0.015; human diploid cell, P = 0.026) and re-exposed time (P = 0.000) exhibited independent effects following booster vaccination. Based on the prediction model, the 99 % individual prediction intervals (IPI) of VNA titres were established at 3, 6, 12 and 18 months for the 12 characteristic populations respectively. The cases of VNA below 0.5 IU/ml first appeared at 6 months in group D of primary vaccinations and at 10 years in group F of boosters. We conclude that for primary vaccination 2-1-1 schedule is more efficient than 5-dose; the use of residual rabies immunoglobulin for distal intramuscular injection isn't recommended. The 99 % IPI of VNA titres could provide the appropriate timing for booster vaccination.