Antibody persistence, 32 years after post-exposure prophylaxis with human diploid cell rabies vaccine (HDCV)

In 1975–1976 forty-five persons severely bitten by rabid wolves and dogs in Iran were treated successfully against rabies with HDCV. In this study contact was made with 26 of 45 above persons, 32 years after their initial treatment and all had rabies neutralizing antibody ranging from 0.3 to 2.69 IU/ml of serum. Of the 26 persons, 17 had received a booster dose of HDCV, 28 years ago and the remaining 9 persons, who had not received any booster since the initial treatment, were given one booster dose of HDCV. All 9 of these patients developed an anamnestic response after their booster inoculation. This study confirms the persistence of rabies neutralizing antibody in persons that received post-exposure vaccination with HDCV, 32 years previously. Furthermore, a single booster inoculation with HDCV resulted in anamnestic response in all individuals.