Comparative safety and immunogenicity of two recombinant hepatitis B vaccines given to infants at two, four and six months of age

Objectives. To evaluate the relative safety and immunogenicity of the two recombinant hepatitis B vaccines licensed in the United States with doses recommended for routine immunization of low risk infants and a schedule that corresponds with routine pediatric visits. Methods. Healthy infants were immunized at 2, 4 and 6 months of age with hepatitis B vaccine manufactured by either SmithKline Beecham (Engerix-B(R), 10 mu g/dose, n = 228) or Merck and Co, (Recombivax HB(R), 2.5 mu g/dose, n = 200). Adverse reactions were ascertained by parental reports and interviews and by review of medical records. Antibody concentrations to hepatitis B surface antigen (anti-HBs) were measured in sequential serum specimens by enzyme immunoassay. Results. Adverse reactions were mild and the rates were not significantly different between the two groups. After the first and second doses the rates of seropositivity (greater than or equal to 1 mIU/ml) and seroprotection (greater than or equal to 10 mIU/ml) were significantly higher in infants given SmithKline Beecham vaccine (P < 0.01). After the second and third doses infants given SmithKline Beecham vaccine also had significantly higher geometric mean anti-HBs concentrations compared with those given Merck vaccine (348.0 mIU/ml vs. 66.9 and 1914.8 mIU/ml vs, 514.8 mIU/ml, respectively, P < 0.001). Nevertheless after the third dose 99% of infants in both vaccine groups achieved seroprotective antibody concentrations. Conclusions. Both recombinant hepatitis B vaccines were safe and immunogenic when administered concurrently with other pediatric vaccines at 2, 4 and 6 months of age, but earlier protective responses were observed with the SmithKline Beecham vaccine than with the Merck vaccine.