Factors affecting rabies virus neutralizing antibody level after vaccination

ObjectiveTo explore the factors affecting rabies virus neutralizing antibodies in vivo after rabies vaccination.

MethodsSerum samples collected from the persons who received rabies vaccination from January to August 2018 were used in rapid fluorescent focus inhibition test (RFFIT) to detect rabies virus neutralizing antibody (RVNA) levels. Statistical analysis was performed by using SPSS 19.0 software.

ResultsA total of 498 serum samples collected after full course rabies vaccination were tested. The RFFIT test results showed that the RVNA geometric mean titer (GMT) was 4.94 IU/ml, and the seropositive rate was 96.18% (479/498). The analysis on the antibody positive rate showed that there were statistical differences among groups with different post vaccination times (χ²＝7.888, P＝0.039). The antibody positive rate in 30–90 d group was higher than that in the 91–180 d group. The results of multivariate analysis showed that age and post vaccination time were important factors affecting RVNA level. Among them, the age was positively correlated with RVNA level, and the post vaccination time was negatively correlated with RVNA level. The post vaccination time had the largest impact on RVNA level, with an impact importance of 0.62.

ConclusionRabies vaccination can produce a reliable immune effect. Age, days after vaccination and other factors have a certain effect on antibody positive rate and RVNA level. In addition to timely and standard post-exposure treatment after rabies exposure, serum antibody level should be regularly tested for populations at high-risk, immunocompromised individuals or people with immunosuppressive diseases. For those with RVNA titers less than 0.5 IU/ml after rabies vaccination, re-vaccination should be given to effectively prevent rabies.