Antibody Persistence of Human Diploid Cell Rabies Vaccine Administrated Using the Four-Versus Five-Dose Essen...

Evidence on long-term antibody persistence for the rabies vaccine administered using the four-dose Essen regimen is lacking. This study compared antibody persistence for the human diploid cell rabies vaccine (HDCV) administered using the four- versus five-dose Essen intramuscular regimen in post-exposure prophylaxis (PEP).

This prospective cohort study enrolled patients vaccinated with the lyophilized HDCV for PEP who were grouped into four-dose and five-dose Essen groups. Rabies virus-neutralizing antibody (RVNA) detection was performed at 1 year or 3 years after initial vaccination.

In total, 180 and 184 patients were included in the four- and five-dose groups, respectively. The 1-year seroconversion (>0.5 IU/mL) rates were similar in the five-dose and four-dose Essen groups (99.2% vs. 98.3%, p = 0.662), as were the 3-year seroconversion rates (98.4% vs. 98.3%, p > 0.999). The median RVNA titer was significantly higher with the five-dose Essen regimen compared with the four-dose Essen regimen at 1 year (2.75 vs. 4.6 IU/mL, p = 0.002), and both groups had similar rates at 3 years (2.00 vs. 3.80 IU/mL, p = 0.443). Multivariable stepwise linear regression analysis showed that the five-dose Essen regimen was independently associated with higher serum RVNA titer compared to the four-dose Essen regimen (β = 0.175, p = 0.001), and 3 years after vaccination, was independently associated with a lower serum RVNA titer compared to 1 year (β = -1.06, p = 0.049).

The four- and five-dose Essen regimens effectively produce durable immunogenicity, supporting the feasibility of implementing the four-dose Essen regimen for rabies immunization in China.