Study of a New Formulation of DTPa-HBV-IPV/Hib Vaccine Administered as a Booster Dose to 18-23 Months Old Children

Inclusion Criteria: * Subjects who the investigator believes that their parents/guardians can and will comply with the requirements of the protocol should be enrolled in the study. * Subjects must have completed full three-dose primary vaccination course with DTPa-HBV-IPV/Hib or DTPa-HBV-IPV in the primary study DTPa-HBV-IPV-109 (study NCT00320463). * A male or female between, and including 18 and 23 months of age at the time of the booster vaccination. * Written informed consent obtained from the parent or guardian of the subject. * Healthy subjects as established by medical history and clinical examination before entering into the study. Exclusion Criteria: * Use of any investigational or non-registered product other than the study vaccines within 30 days preceding the booster dose of study vaccine, or planned use during the study period. * Chronic administration of immunosuppressants or other immune-modifying drugs within six months prior to the booster dose. * Planned administration/ administration of a vaccine not foreseen by the study protocol within 30 days of the booster dose. * Participation in another clinical study, between the primary study NCT00320463 and the present booster study, or at any time during the study, in which the subject has been or will be exposed to an investigational or a non-investigational product. * Previous booster vaccination against diphtheria, tetanus, pertussis, poliomyelitis and hepatitis B since the conclusion visit of study NCT00320463. * Previous booster vaccination against Haemophilus influenzae diseases in the DTPa-HBV-IPV/Hib groups, since the conclusion visit of study NCT00320463. * History of exposure to diphtheria, tetanus, pertussis, poliomyelitis, hepatitis B and/or Haemophilus influenzae disease since the conclusion visit of study NCT00320463. * Any confirmed or suspected immunosuppressive or immunodeficient condition, based on physical examination. * History of allergic disease or reactions likely to be exacerbated by any component of the vaccines. * Acute disease at the time of enrolment. * Administration of immunoglobulins and/or any blood products within the three months preceding the booster dose or planned administration during the study period. * Any of the following adverse events having occurred after previous administration of DTP vaccine: * Hypersensitivity reaction due to the vaccine. * Encephalopathy defined as an acute, severe central nervous system disorder of unknown etiology occurring within 7 days following previous vaccination and generally consisting of major alterations in consciousness, unresponsiveness, generalized or focal seizures that persist more than a few hours, with failure to recover within 24 hours. * Any of the following adverse events having occurred after previous administration of DTP vaccine: * Temperature of \>= 40.0 °C (axillary temperature), within 48 hours of vaccination. * Collapse or shock-like state within 48 hours of vaccination. * Persistent, inconsolable crying lasting \>= 3 hours, occurring within 48 hours of vaccination. * Convulsions with or without fever, occurring within 3 days of vaccination