Immunogenicity and safety of a pediatric dose of a virosomal hepatitis A vaccine in healthy children in India.

As India is transitioning from high to intermediate hepatitis A endemicity, the need for hepatitis A vaccination programs increases. This study investigated the immunogenicity and safety of a virosomal hepatitis A vaccine (HAVpur Junior) compared with an aluminum-adsorbed hepatitis A vaccine (Havrix 720 Junior) in Indian children. Healthy children aged 18-47 months, stratified by age, were randomized to either HAVpur Junior or Havrix 720 Junior. The first dose of vaccine was administered on Day 1 and the second (booster) dose 6 months later. Antibodies against hepatitis A virus (HAV) were measured using a microparticle enzyme immunoassay. The primary objective assessed non-inferiority of HAVpur Junior to Havrix 720 Junior in terms of seroprotection rates (≥ 10 mIU/mL anti-HAV antibodies) at 1 month after the first vaccination. Non-inferiority was demonstrated if the lower limit of the 90% confidence interval of the group difference was greater than -10%. Local and systemic adverse events were recorded. The seroprotection rate at 1 month was 95.9% in the HAVpur Junior group and 96.6% in the Havrix 720 Junior group. As the lower limit of the 90% confidence interval of the group difference was greater than -10% (-4.7), non-inferiority of HAVpur Junior to Havrix 720 Junior was established. The overall incidence of adverse events (solicited and unsolicited) after each vaccination was similar in both groups. In conclusion, the aluminum-free virosomal vaccine HAVpur Junior induced a similar immune response to Havrix 720 Junior in healthy Indian children aged 18 to 47 months. Both vaccines were well tolerated. The study shows that the low-dose virosomal HAV vaccine is consistently efficacious and well tolerated in children of all age groups and is suitable for inclusion into Indian childhood vaccination schedules.