 All participants will receive a total 4 doses of Hep B, i.e. one dose of Hep B monovalent vaccine given at birth followed by 3 doses of Sanofi Pasteurs hexavalent vaccine given at 6, 10 and 14 weeks of age in the context of the study. Participants and parents will attend four clinic visits; the expected participation in the study is approximately 3 months. 