COMPARATIVE SAFETY AND IMMUNOGENICITY OF 2 RECOMBINANT HEPATITIS-B VACCINES GIVEN TO INFANTS AT 2, 4 AND 6 MONTHS OF AGE

Objectives. To evaluate the relative safety and immunogenicity of the two recombinant hepatitis B vaccines licensed in the United States wit h doses recommended for routine immunization of low risk infants and a schedule that corresponds with routine pediatric visits. Methods. Hea lthy 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 g roups. After the first and second doses the rates of seropositivity (g reater than or equal to 1 mIU/ml) and seroprotection (greater than or equal to 10 mIU/ml) were significantly higher in infants given SmithKl ine Beecham vaccine (P < 0.01). After the second and third doses infan ts given SmithKline Beecham vaccine also had significantly higher geom etric mean anti-HBs concentrations compared with those given Merck vac cine (348.0 mIU/ml vs. 66.9 and 1914.8 mIU/ml vs, 514.8 mIU/ml, respec tively, P < 0.001). Nevertheless after the third dose 99% of infants i n both vaccine groups achieved seroprotective antibody concentrations. Conclusions. Both recombinant hepatitis B vaccines were safe and immu nogenic when administered concurrently with other pediatric vaccines a t 2, 4 and 6 months of age, but earlier protective responses were obse rved with the SmithKline Beecham vaccine than with the Merck vaccine.