Economical Regimens of Human Diploid Cell Strain Antirabies Vaccine for Post-Exposure Prophylaxis

Summary

One hundred and seventy-nine Thai subjects with no history of rabies vaccination were inoculated either with a) Semple vaccine alone, b) one of various economical, candidate regimens for human diploid cell strain rabies vaccine (HDCSV) alone, c) or vaccine and human rabies immune globulin (HRIG) given at a dosage of 40 IU/kg on day 0. Rabies lgG antibodies were measured by enzyme immunoassay (Elisa) on samples taken from each group of volunteers on days 0, 7, 14, 28, 91 and, for some groups, day 182.

Results are reported showing that one-tenth of the normal dose of HDCSV administered intradermally (id), or subcutaneously (sc) with Al (OH)₃ as adjuvant, on days 0, 3, 7, 14, 28 and 91 is a relatively poor antigenic stimulus. By contrast, high titres were evoked by small doses given at multiple sites (4 or 8) on day 0, either by the id route, or by the sc route with or without adjuvant. One of the regimens tested, which uses a total of only 1.4-ml of HDCSV given on days 0, 7, 28 and 91, stimulated a rapid and high-titred antibody response sufficient to justify its evaluation in persons genuinely exposed to rabies.