Studies on Japanese-produced chick embryo cell culture rabies vaccines.

We studied the potency, antibody response, and side reactions of commercial Japanese chick embryo cell (CEC) rabies vaccines for humans. The CEC rabies vaccines had indexes of 10(5.1) and 10(6.0) in Habel tests, and have had potencies higher than those of the International Reference Vaccine II by National Institutes of Health (NIH) tests. Thirty healthy adults received 1 ml of the CEC rabies vaccines subcutaneously as primary immunization on days 0 and 7. Between six and 12 months after the primary immunization, 22 of the 30 subjects showed neutralizing antibody levels greater than or equal to 1:40 by the rapid fluorescent focus inhibition test (RFFIT). The 30 subjects had been given booster immunizations of the CEC rabies vaccines at 8-14 months in addition to the primary immunization. Six to 12 months after the booster immunizations, 27 of the 30 subjects showed antibody levels greater than or equal to 1:40. No severe side reactions were reported during the course of vaccination. Thus we conclude that CEC rabies vaccine is effective and safe for pre-exposure immunization.