Immunogenicity and reactogenicity of a combined high dose hepatitis A and hepatitis B vaccine, compared to that of Twinrix™ in healthy Indian children

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(TM) (GlaxoSmithKline Biologicals, Rixensart, Belgium) schedule intramuscularly. The seroconversion (greater than or equal to1 MIU/ml for anti-HBs antibodies and greater than or equal to33 MIU/ml for anti-HAV antibodies) and seroprotection (anti-HBs greater than or equal to 10 MIU/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 I 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 II, 53% (52/98) of the documented doses compared to 37% (54/146) in Group II (P = 0.018). Conclusion: TwinrixTM vaccine is safe and highly immunogenic in Indian children, Further study of the high dose vaccine would deter-mine if its two dose regimen is a feasible advantage. (C) 2002 Elsevier Science Ltd. All rights reserved.