Long term (24 months) follow-up of a hepatitis A and B vaccine, comparing a two and three dose schedule in adolescents aged 12-15 years.

BACKGROUND: A two dose schedule (0 and 6 months) for a combined hepatitis A and B vaccine is currently being developed. METHODS: The present study compared the combined hepatitis A and B vaccines in 12-15-year-old: Twinrix paediatric (360 EL.U HAV antigen/10 microg HBs antigen) on a three dose schedule (0, 1 and 6 months) to the adult formulation (720 EL.U HAV antigen/20 microg HBs antigen) on a two dose schedule (0 and 6 months) and also reports on the follow-up until 24 months. RESULTS: Seroconversion (SC) rates to HAV in both regimens reached 100% by month 7 and remained 100% up to month 24. Anti-HAV, GMTs were slightly higher for the two dose than the three dose regimens at this time point. Seroprotection against hepatitis B was >99% in both groups by month 7 and 24, this was still 94 and 96%, respectively. Statistical non-inferiority of group 1 (two dose) versus group 2 (three dose) was demonstrated. All vaccines were well tolerated and the most frequently reported local and general symptoms were pain and fatigue. There were no vaccine-related serious adverse events reported during the study. CONCLUSION: The two dose regimen elicited similar immunogenicity to HAV and HBsAg and reactogenicity profiles as the three dose regimen in this group of healthy adolescents. The reduction in the number of doses from the current three dose schedule will make vaccination against hepatitis A and B more convenient to the vaccinee, reduce healthcare staff time required and may lower the overall costs associated with vaccination.