In order to reduce the amount of thiomersal in its vaccines, GSK Biologicals has developed a DTPw-HBV vaccine with low thiomersal content (Tritanrix™- HepB low thio). This vaccine is to be used in combination with a Hib low dose vaccine containing 2.5µg of PRP antigen (Hib 2.5). The purpose of this study is to generate clinical data with Tritanrix™-HepB low thio vaccine when extemporaneously mixed with Hib 2.5 vaccine. The control group will receive Tritanrix™-HepB/Hiberix™.

Subjects received primary vaccination in study 208108/091 (double blind). Of these subjects 50% were randomised to participate in the PRP challenge study (208108/092) (open), and all subjects will be invited to participate in a booster study DTPWHBV=HIB2.5-093 (101477).

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.
• A male or female between, and including, 6 and 8 weeks of age at the time of the first vaccination.
• Written informed consent obtained from the parent or guardian of the subject.
• Free of obvious health problems as established by medical history and clinical examination before entering into the study.
• Born after a gestation period of 36 to 42 weeks.
• Born to a mother proven seronegative for HBsAg.

Exclusion Criteria:

• Planned administration/ administration of a vaccine not foreseen by the study protocol within 30 days before each dose of vaccine, with the exception of oral polio vaccine (OPV).
• Bacille Calmette-Guérin (BCG) vaccine received after the first 2 weeks of life.
• Use of any investigational or non-registered drug or vaccine other than the study vaccine(s) within 30 days preceding the first dose of study vaccine, or planned use during the study period.
• Chronic administration of immunosuppressants or other immune-modifying drugs since birth.
• Previous vaccination against diphtheria, tetanus, pertussis, hepatitis B and/or Hib.
• History of, or intercurrent, diphtheria, tetanus, pertussis, hepatitis B and/or Hib disease.
• Any confirmed or suspected immunosuppressive or immunodeficient condition, including human immunodeficiency virus (HIV) infection.
• A family history of congenital or hereditary immunodeficiency.
• History of allergic disease or reactions likely to be exacerbated by any component of the vaccine.
• Major congenital defects or serious chronic illness.
• History of any neurologic disorders or seizures.
• Acute disease at the time of enrolment.
• Acute or chronic, clinically significant pulmonary, cardiovascular, hepatic or renal functional abnormality, as determined by physical examination or history.
• Administration of immunoglobulins and/or any blood products since birth or planned administration during the study period.
• Other conditions which in the opinion of the investigator may potentially interfere with interpretation of study outcomes.

Patient-level data for this study will be made available through www.clinicalstudydatarequest.com following the timelines and process described on this site.