Immunogenicity and Safety of Sanofi Pasteur's Combined Vaccine Given as a Three-Dose Primary Series at 2, 3,4 Months of Age and Followed by a Booster Dose Given at 16 to 17 Months of Age in Vietnamese Infants Who Previously Received a Dose of Hepatitis B Vaccine at Birth or Within 1 Week After Birth

The purpose of this study is to describe the immunogenicity and safety of Sanofi Pasteur's DTaP-IPV-Hep B-PRP-T fully liquid combined hexavalent vaccine (Hexaxim®) administered at 2, 3, and 4 months of age and at 16 to 17 months of age in infants and toddlers who received a dose of Hep B vaccine at birth or within 1 week after birth.

Primary Objective:

* To describe the safety profile after each and all doses of Sanofi-Pasteur's DTaP-IPV-Hep B-PRP-T combined vaccine in Vietnamese infants and toddlers.

Secondary Objective:

* To demonstrate the non-inferiority of the immune response to all antigens induced by the study vaccine in Vietnamese infants one month after the third dose in a 3-dose primary series with the immune response to all antigens induced by the same study vaccine outside Vietnam.
* To evaluate the immunogenicity of the study vaccine one month after the 3-dose primary series.
* To describe the persistence of all antibodies before receipt of the booster vaccination.
* To evaluate the immunogenicity of the study vaccine one month after the booster.

Participants will receive a total of 5 doses of Hep B: One dose of Hep B monovalent vaccine given at birth or within 1 week after birth followed by 3 doses of the Sanofi Pasteur's hexavalent vaccine given as primary series at 2, 3, and 4 months of age and then a booster dose at 16 to 17 months of age, to comply with Vietnamese vaccination recommendations.

Eligibility Criteria:
Inclusion Criteria:

* Aged 61 to 91 days on the day of the first study visit
* Born at full term of pregnancy (≥ 37 weeks) and with a birth weight ≥2.5 kg
* Informed consent form has been signed and dated by the parent(s) or other legally acceptable representative (and by an independent witness if required by local regulations)
* Subject and parent/legally acceptable representative are able to attend all scheduled visits and to comply with all trial procedures
* Have received one dose of Hep B vaccine at birth or within 1 week after birth (documented according to the national recommendations).

Exclusion Criteria:

* Participation in the 4 weeks preceding the first trial vaccination or planned participation during the present trial period in another clinical trial investigating a vaccine, drug, medical device, or medical procedure
* Receipt of any vaccine in the 4 weeks preceding the first trial vaccination or planned receipt of any other vaccine within the period from 8 days before to 8 days after each subsequent trial vaccination except for Bacille Calmette Guerin (BCG) vaccination (any administration of oral poliovirus vaccine (OPV) in the context of oral poliovirus vaccine-national immunization days (NIDs) does not fall within the scope of this exclusion criterion)
* Previous vaccination against diphtheria, tetanus, pertussis, poliomyelitis, hepatitis B (except the dose of Hep B vaccine given at birth or within 1 week after birth) diseases or Haemophilus influenzae type b infection with either the trial vaccine or another vaccine (any administration of OPV in the context of OPV-NIDs does not fall within the scope of this exclusion criterion)
* Past or current receipt of immune globulins, blood or blood-derived products or planned administration during the trial
* Known or suspected congenital or acquired immunodeficiency; or receipt of immunosuppressive therapy, such as anti-cancer chemotherapy or radiation therapy since birth; or long-term systemic corticosteroid therapy (prednisone or equivalent for more than 2 consecutive weeks since birth)
* History of diphtheria, tetanus, pertussis, poliomyelitis, hepatitis B, or Haemophilus influenzae type b infections (confirmed either clinically, serologically or microbiologically)
* Known personal or maternal history of Human Immunodeficiency Virus (HIV), or hepatitis C seropositivity
* Known systemic hypersensitivity to any of the vaccine components, or history of a life-threatening reaction to the vaccine used in the trial or to a vaccine containing any of the same substances
* Known thrombocytopenia, as reported by the parent/legally acceptable representative
* Bleeding disorder, or receipt of anticoagulants in the 3 weeks preceding inclusion, contraindicating intramuscular vaccination
* History of seizures
* In an emergency setting, or hospitalized involuntarily
* Chronic illness that, in the opinion of the investigator, is at a stage where it might interfere with trial conduct or completion
* Moderate or severe acute illness/infection (according to investigator judgment) on the day of vaccination or febrile illness (temperature ≥38.0°C). A prospective subject should not be included in the study until the condition has resolved or the febrile event has subsided
* Identified as a natural or adopted child of the Investigator, relatives or employee with direct involvement in the proposed study.