Comparison of two recombinant hepatitis B vaccines and their interchangeability in Argentine infants.

OBJECTIVE To compare two pediatric recombinant hepatitis B vaccines-the Engerix-B reference vaccine and the Euvax-B vaccine-in terms of immunogenicity and reactogenicity, and also to investigate their interchangeability, that is, whether a three-dose hepatitis B vaccination schedule begun with a first dose of Engerix-B could be completed with two doses of Euvax-B. METHODS This study was conducted in the city of Córdoba, Argentina, from March 1999 through February 2000. Three groups of Argentine newborns (100 per group) were vaccinated at 0, 1, and 6 months of age with hepatitis B vaccine: group A, three doses of Euvax-B; group B, three doses of Engerix-B; and group C, one dose of Engerix-B followed by two doses of Euvax-B. Reactogenicity was evaluated based on parental reporting of any solicited local or systemic event occurring during the 7-day period following vaccination. Whether Euvax-B and Engerix-B were clinically identical was assessed in terms of the seroprotection rates (antibodies to hepatitis B surface antigen (anti-HBsAg) >/= 10 milli-international units per mL (mIU/mL) 2 months after the third vaccination). RESULTS Reactogenicity was low in all three groups. Five months after the second dose (that is, immediately prior to the third vaccination), seroprotection rates were 95.9%, 94.7%, and 90.2% for groups A, B, and C, respectively. Two months after the third dose all subjects were seroprotected, with geometric mean concentrations of anti-HBsAg of 2 468.1, 1 714.8, and 2 075.3 mIU/mL for groups A, B, and C, respectively. CONCLUSIONS Both of the recombinant hepatitis B vaccines that we studied were well tolerated and highly immunogenic. Euvax-B was clinically identical (not inferior) to the EngerixB reference vaccine, and either vaccine could be used to achieve the World Health Organization goal of immunizing all infants against hepatitis B. Further, Euvax-B can be safely used in infants given an initial dose of either Euvax-B or Engerix-B.