Anti-rabies antibody titers among subjects who received rabies post-exposure prophylaxis with foreign-made rabies vaccines at the beginning and followed with Japanese rabies vaccine

Recently travelers who were bitten by possibly rabid animals in rabies endemic regions and returned to Japan have increased in number. About half of them received rabies post-exposure prophylaxis (RPEP) with one or more doses of foreign-made rabies vaccines (FRV) in the local medical institutions. FRV, however, are not available in Japan so we have to continue the RPEP with Japanese rabies vaccine (JRV). It has not been demonstrated that an anti-rabies antibody induced with JRV following Vero cell rabies vaccine (PVRV) or chick embryo cell rabies vaccine (PCEC) could be high enough to prevent clinical rabies. We examined anti-rabies antibody (ARA) titers among the subjects visited our vaccine clinic to receive RPEP and obtained results as follows: the ARA titers after a total of 5 doses of PCEC or PVRV and JRV were high enough to prevent clinical rabies as after 5 doses of JRV. However, ARA titers obtained after receiving one dose of PVRV and 2 doses of JRV seemed lower than those produced after one dose of PCEC and 2 doses of JRV or 3 doses of JRV. To accelerate antibody production, consequently, the simultaneous intradermal and subcutaneous injection method of rabies vaccine may be applied to those who were bitten in their hands or head by possibly rabid animals and received only one dose of PVRV in rabies endemic regions.