Phase III Study of Intramuscular TAK-816 in Healthy Infants

Inclusion Criteria: 1. Healthy Japanese infants. 2. Male or female infants aged 2-6 months (≥2 and \<7 months) at the time of the first dose of investigational product (excluding hospitalized infants). 3. Infants whose parents or legal guardians have agreed to cooperate with the investigator during the study period. 4. The legal guardian signed and dated a written, informed consent form prior to the initiation of any study procedures. 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. Previously diagnosed immunodeficiency. 5. Documented history of anaphylaxis to any ingredients of the investigational product (e.g., diphtheria toxoid). 6. A history of convulsions. 7. Previous administration of another Hib vaccine. 8. 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. 9. Prior participation in any clinical study or post-marketing clinical study. 10. Previously receipt of blood transfusions, gamma globulin preparations (except monoclonal antibody products not containing any components of Hib as antigens), systemic immunosuppressive therapy, or systemic corticosteroids, or a plan to receive any of these products during the study period. 11. Presence of thrombocytopenia or coagulopathy. 12. Children considered ineligible for the study for other reasons by the investigator or subinvestigator.