COMPARISON OF THE SAFETY AND IMMUNOGENICITY OF 2 INACTIVATED HEPATITIS-A VACCINES

Two inactivated hepatitis A vaccines, Avaxim(TM) and Havrix(TM) 1440, were compared in a two-center, randomized, open trial. Two doses of ei ther vaccine were given 6 months apart to 423 healthy adults. Voluntee rs were randomized in each center by sex, age (younger or older than 4 0 years), and weight (more or less than 77 kg). Antibodies were titrat ed in a blinded manner by an independent laboratory with a modified ra dioimmunoassay. Both populations were still comparable even after excl usion of subjects with positive preimmunization antihepatitis A virus (HAV) titers (n = 83) and those who violated the protocol. Two weeks a fter the first dose, the seroconversion rates of initially HAV-seroneg ative individuals (antibody titer <20 mlU/mL) were 96% in those receiv ing Avaxim(TM) and 87% in the Havrix(TM) 1440 group. A logistic regres sion analysis demonstrated that seroconversion rates at week 2 were si gnificantly higher with Avaxim(TM) (P<.01). The corresponding geometri c mean titers (GMT) of 53.1 and 36.4 mlU/mL, respectively, rose to 114 and 75 mlU/mL 8 weeks after the first dose. At the time of the booste r dose, seroconversion rates were 100% in the Avaxim(TM) group and 97. 6% in the Havrix(TM) 1440 group; corresponding GMTs were 172 and 100 m lU/mL. A 25-fold increase in GMT was observed in each group 4 weeks af ter the booster dose. Local reactions were reported by 15.1% of the Av axim(TM) vaccinees and 30.1% of Havrix(TM) 1440 vaccinees after the fi rst dose, and by 15.2% and 22.2% of vaccinees after the booster dose ( P<.01 after each injection). Rates of systemic reactions were 19.3% (A vaxim(TM)) and 32.4% (Havrix(TM) 1440 group) after the first dose, and 13.4% and 15.2% after the booster dose. This comparative trial demons trated that Avaxim(TM) has overall a superior safety and immunogenicit y profile to that of Havrix(TM) 1440.