Preexposure Immunization With Intradermal Human Diploid Cell Rabies Vaccine

Abstract

Intradermal human diploid cell rabies vaccine (ID HDCV) was licensed for preexposure use in the United States on May 30, 1986. We studied the safety and efficacy of this newly approved route and dose of administration. Serologic results were available from 112 (90%) of the 124 persons who participated in an HDCV low-dose preexposure study in which five different ID, intramuscular (IM), and subcutaneous primary immunization regimens were administered. Three 1.0-mL IM doses of vaccine resulted in titers similar to those from three 0.1-mL ID doses when compared 49 days, one year, and two years after primary immunization. Uniformly high postbooster titers occurred in all five groups when ID boosters were administered at one year or two years. Adverse reactions were similar following both ID and IM vaccination. Although ID HDCV can be a cost-effective substitute for IM vaccine, excessive use of unnecessary preexposure booster doses by any route may be inadvisable because of systemic allergic reactions. In addition, poor immune responses to HDCV have been documented in persons vaccinated in some developing countries. This may limit the use of low-dose regimens in some places.