Randomized, cross-over, controlled comparison of two inactivated hepatitis A vaccines

The immunogenicity, tolerability and interchangeability of two hepatitis A vaccines, Vaqta (Merck and Co.) and Havrix (SmithKline) were studied in a randomized, crossover, controlled clinical trial. Vaccine was administered to 201 volunteers at 0 and 26 weeks in one of four vaccine regimens: Havrix-Havrix; Havrix-Vaqta; Vaqta-Havrix or Vaqta-Vaqta. Seroconversion rates (≥10 mIU/ml) for those whose first dose was Vaqta or Havrix, respectively, were: 41/96 (43%) versus 30/95 (32%) ( P=0.15) at 2 weeks and 91/98 (93%) versus 84/97 (87%) ( P=0.43) at 4 weeks, and 100% at 26 weeks. Geometric mean concentrations (GMC) of total antibody to hepatitis A virus (anti-HAV) for Vaqta and Havrix were 189 and 114 mIU/ml ( P=0.011) at 4 weeks and 234 and 136 mIU/ml ( P