Background and aims: Hepatitis A virus (HAV) and hepatitis B virus (HBV) are vaccine preventable important childhood acquired infectious diseases in developing countries. In the changing epidemiology of HAV, the utility of such a vaccine in India needs urgent attention. Further, the efficacy of two versus three dose schedule needs to be assessed to improve compliance.
Subjects and methods: One hundred healthy school children, aged 1-15 years were recruited in a randomised open study to receive either vaccination schedule: Group I: combined high-dose hepatitis A and B vaccine to be administered on a 0, 6 month schedule intramuscularly; Group II: to be administered on 0, 1, 6 month Twinrix (GlaxoSmithKline Biologicals, Rixensart, Belgium) schedule intramuscularly. The seroconversion (> or =1MIU/ml for anti-HBs antibodies and > or =33MIU/ml for anti-HAV antibodies) and seroprotection (anti-HBs > or =10MIU/ml after the third dose of vaccine) rates were determined at months 1, 2, and 7.
Results: The mean age and gender was similar between groups: 7.9+/-2.6 years (range 3-15 years). At month 7 all subjects (100%) in both groups were seropositive for anti-HAV antibodies, Group I had higher anti-HAV titres at months 1 or 2 compared to Group II (P=0.025, P=0.040). Group II developed higher seroprotection rates (month 2, P=0.002, month 6, P=0.003) compared to Group I and higher titres (month 2, P=0.001, month 6 P=0.001) compared to Group I. At month 7, the geometric mean titres (GMTs) were comparable between groups and seroprotection reached 100% in both the groups. The incidence of any symptom per dose analysis reported during a 4-day follow-up period was significantly higher in Group I, 53% (52/98) of the documented doses compared to 37% (54/146) in Group II (P=0.018).
Conclusion: Twinrix vaccine is safe and highly immunogenic in Indian children. Further study of the high dose vaccine would determine if its two dose regimen is a feasible advantage.