Two-Dose Combined Vaccination against Hepatitis A and B in Healthy Subjects Aged 11-18 Years

BACKGROUND: In this open, randomized trial the safety, reactogenicity, and immunogenicity profile of a high-dose combined hepatitis A and B candidate vaccine was compared with that of Twinrix Paediatric in healthy volunteers aged 11-18 years. METHODS: One hundred subjects were randomly allocated to either of two groups. One group received the high-dose vaccine (720 E1.U HAV antigen; 20 microg hepatitis B surface antigen (HBsAg) at months 0 and 6; the second group received Twinrix Paediatric (360 E1.U HAV antigen; 10 microg HBsAg), following a 0-1-6-month schedule. RESULTS: Injection site soreness and fatigue were the most frequently reported solicited symptoms. For hepatitis A all subjects had seroconverted at month 7, and geometric mean titres (GMT) were 8,151 mIU/ml in the high-dose group and 6,394 mIU/ml in the Twinrix Paediatric group. For hepatitis B the GMT for the Twinrix Paediatric group was significantly higher at month 2 and month 6. However, no difference in GMT between groups could be established at month 7. The seroprotection rate attained 100% in both groups, and GMT were 4,212 mIU/ml (high-dose group) and 6,330 mIU/ml (Twinrix Paediatric). CONCLUSIONS: The two vaccines showed similar safety and reactogenicity profiles. After completion of the vaccination schedule, no difference in immunogenicity was shown. This high-dose vaccine, administered following a two-dose schedule, can be considered an alternative regimen for the immunization of healthy adolescents against hepatitis A and hepatitis B infections, in a setting where vaccinees are not immediately at risk of exposure to hepatitis B.