Immunogenicity and adverse effects of inactivated virosome versus alum-adsorbed hepatitis A vaccine: A randomized controlled trial

Immunogenicity and adverse effects of a novel inactivated hepatitis A vaccine based on virosomes (IRIV-HAV) was compared with a standard vaccine adsorbed to aluminium (Al-HAV). Seronegative volunteers (n = 301) were randomly allocated to one injection of IRIV-HAV or to two injections of Al-HAV, followed by a booster injection at 12 months. Two hundred and ninety-eight (99%) completed the first month and 215 (71%) could be evaluated at I year. Geometric mean antibody concentrations at days 0, 14 and at 12 months were similar in the two vaccine groups. Lower antibody concentrations were recorded with IRIV-HAV at day 28 (P < 0.0001) and at 13 months (P = 0.02). Seroconversion to protective antibody levels, however, was similar (98% at day 28, 94% at 12 months, 100% at 13 months), Local adverse effects were reported in 17% with IRIV-HAV but in 66% with Al-HAV (P < 0.0001) after the initial vaccination and in 32% and 42% following the booster vaccination (p = 0.05). In conclusion, IRIV-HAV may provide similar protection but cause less local adverse effects.