Studies in Europe (1-6) and in the United States (7,8) to investigate the efficacy and safety of low dose intradermal vaccination schedules have shown that satisfactory levels of antibody were produced in all subjects with two or more inoculations.

Studies in the United States (7,8,9) using three doses of Mérieux's Rabies Vaccine demonstrated adequate rabies antibody titers in 100% of persons receiving intradermal injections. The geometric mean titer in these subiects 49 days after immunization was approximately 7.5 to 8.9 I. U. compared with 12.9 to 13.8 I. U. in controls receiving 1.0 ml of vaccine intramuscularly (7).

The definition of a minimally acceptable antibody titer varies both among laboratories and according to the purposes for which immunization is given. The Centers for Disease Control (CDC) currently specifies complete virus neutralization at a 1:5 serum dilution in the rapid fluorescent focus inhibition test (RFFIT) as an acceptable response to pre-exposure immunization. After studies of post-exposure immunization, the World Health Organization (WHO) specifies a titer of 0.5 I. U. as an acceptable response.

Bookmark this page: