title: Randomized, cross-over, controlled comparison of two inactivated hepatitis A vaccines.
abstract: 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<0.001) at 26 weeks. At 30 weeks, the GMC after two doses of Havrix was 2612 mIU/ml compared with 5497 after two doses of Vaqta (P<0.001). The GMC in the Havrix-Vaqta group was 5672 mIU/ml compared with 3077 mIU/ml in the Vaqta-Havrix group (P<0.001). Less than half of vaccine recipients reported tenderness or pain. In this study, seroconversion rates of the two vaccines were similar. Vaqta produces significantly higher anti-HAV antibody than Havrix. Crossover immunization is well tolerated and results in high antibody concentrations, especially when Vaqta is the booster dose. The significance of higher anti-HAV antibody concentrations in terms of long-term protection is unknown.
authors: Department of Preventive Medicine and Biometrics, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814-4799, USA. jbryan@usuhs.mil
authors: J P
authors: JP
authors: Bryan
authors: C H
authors: CH
authors: Henry
authors: A G
authors: AG
authors: Hoffman
authors: J E
authors: JE
authors: South-Paul
authors: J A
authors: JA
authors: Smith
authors: D
authors: D
authors: Cruess
authors: J M
authors: JM
authors: Spieker
authors: M
authors: M
authors: de Medina
mesh_terms: D000328:Adult; D000368:Aged; D018592:Cross-Over Studies; D005260:Female; D035922:Hepatitis A Antibodies; D022362:Hepatitis A Vaccines / Q000008:administration & dosage / Q000009:adverse effects / Q000494:pharmacology*; D006508:Hepatitis Antibodies / Q000097:blood; D006801:Humans; D008297:Male; D008875:Middle Aged; D013997:Time Factors; D015164:Vaccines, Inactivated / Q000008:administration & dosage / Q000009:adverse effects / Q000494:pharmacology
chemical_list: D035922:Hepatitis A Antibodies; D022362:Hepatitis A Vaccines; D006508:Hepatitis Antibodies; D015164:Vaccines, Inactivated