The purpose of this study is to evaluate the efficacy (immunogenicity) of TAK-816 when administered to healthy Japanese infants as multiple subcutaneous doses.

Haemophilus Influenzae type b (Hib) is one of the major causes of infectious meningitis in children, and can also cause sepsis, cellulitis, arthritis, epiglottitis, pneumonia and myelitis.

TAK-816 is a conjugated Hib vaccine being tested in healthy infants aged 3-6 months at the time of the first dose.

The objective of this study is to evaluate the efficacy (immunogenicity) and safety of TAK-816 (10 ϻg/0.5 mL) in comparison with ActHIB (Haemophilus b Conjugate Vaccine) as a control.

In addition, the efficacy (immunogenicity) and safety of Absorbed Diphtheria-Purified Pertussis-Tetanus Combined (DPT-TAKEDA) vaccine when TAK-816 and DPT vaccine are administered concomitantly will also be investigated.

For the Primary Immunization Phase of this study: three doses of TAK-816 or ActHIB 10 µg/0.5 mL and DPT-TAKEDA 0.5 mL will be administered at 4-week intervals over 8 weeks (Visit 1, 2, 3). At4 weeks after the third dose, a follow-up observation and evaluation will be made (Visit 4).

For the Booster Vaccination Phase of this study: a single dose of TAK-816 or ActHIB 10 µg/0.5 mL and DPT-TAKEDA 0.5 mL will be given at 52 weeks after the third dose (Visit 5). At 4 weeks after the fourth dose, a follow-up observation and evaluation will be made (Visit 6).

Inclusion Criteria:

1. Male or female infants aged ≥3 and <7 months (excluding hospitalized infants).
2. Infants whose legal acceptable representatives have given informed consent to the study prior to enrollment.
3. Infants whose parents or legal guardians have agreed to cooperate with the investigator during the study period.

Exclusion Criteria:

1. Any serious acute illness.
2. Any underlying cardiovascular, renal, hepatic, or hematologic disease, and/or developmental disorder.
3. History of possible Haemophilus influenzae type b (Hib) infection.
4. History of possible pertussis, diphtheria or tetanus infection.
5. Previously diagnosed immunodeficiency.
6. A documented history of anaphylaxis to any ingredient of the investigational products (TAK-816, ActHIB or DPT-TAKEDA).
7. A history of convulsions.
8. Previous administration of another Hib vaccine.
9. Previous administration of any other vaccine containing any of the components of polio, diphtheria, pertussis, or tetanus.
10. Treatment with any live vaccine during the 27 days before the first dose of TAK-816 or with any inactivated vaccine during the 6 days before dosing.