HEPATITIS-A VACCINATION BY INTRACUTANEOUS LOW-DOSE ADMINISTRATION - ALESS EXPENSIVE ALTERNATIVE

We investigated the immune response to three different intracutaneous (i.c.) doses of inactivated hepatitis A vaccine: 72, 144, and 216 ELIS A units (EU). The response was measured using a quotient score derived from a Commercial enzyme-linked immunosorbent assay (HAVAB Abbott) an d translated to IU per liter using a World Health Organization standar d serum for hepatitis A virus antibody, The results were compared with the results obtained after an intramuscular (i.m.) full dose, i.e. 1, 440 EU, at 0 and 6-12 months. As estimated from antibody concentration , 3 lots of 144 EU i.c. with 100% or two lots of 216 EU i.c. with 98% seroconversion results in at least as goad early protection as the sta ndard immunization with one lot of 1,440 EU i.m., (79% with our method ), Indeed, only two doses of 144 EU vaccine (90% seroconversion) seem to give results comparable to the standard procedure. After the booste r dose the median antibody concentration is 1,290 IU/I for the 144 EU vaccine and 837 for the 216 EU one, compared with an antibody response of 990 IU/I for the standard 1,440 EU i.m, vaccination. In conclusion , three doses of 144 EU vaccine i.c, or, as an alternative, two doses of 216 EU at monthly intervals give good early protection (e.g, before travel). After the booster dose, which is given 6 months to I year la ter, the serological response is comparable to the standard procedure of two doses of the 1,440 EU vaccine given i.m. and with 100% seroconv ersion in all three programs.