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 (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.