Immunogenicity and safety of a new inactivated hepatitis A vaccine: a clinical trial with comparison of administration route.

A bicentre, controlled, randomized, open trial was carried out in order to compare the immunogenicity and the reactogenicity of PASTEUR MERIEUX Sérums et Vaccins inactivated Hepatitis A Vaccine on adults, when used with different routes of administration [intramuscular (i.m.), subcutaneous (s.c.) and needless injection using a Jet injector device]. Vaccines were given at two doses 6 months apart to 147 seronegative subjects. Anti-Hepatitis A virus (HAV) titres were performed at each visit by modified radioimmunoassay assay. After the first dose, 138 subjects except one seroconverted (s.c.). After booster dose, all subjects exhibited high levels of HAV antibodies. The higher titres were observed with Jet injector (GMT: 305 mIU ml-1 after the first dose and 3727 mIU ml-1 after the booster dose), followed by the i.m. route (210 mIU ml-1, 3152 mIU ml-1) and the s.c. route (165 mIU ml-1, 2082 mIU ml-1). No statistically significant differences were observed in the three paired comparisons (i.m. vs jet injector; jet vs s.c., im vs s. c.). This inactivated hepatitis A vaccine appeared to be highly immunogenic after one single dose and one booster 6 months later.