This study will evaluate the safety and efficacy of two doses of two commercially available vaccines used to prevent Haemophilus influenzae type b infections in children 6-12 months of age.

Inclusion Criteria:

• Infants 6-12 months of age.

Exclusion Criteria:

• Prior Hib vaccine administration.
• History of serious reaction(s) following vaccination.
• Any vaccination within 14 days of study vaccination.
• Known or suspected immune impairment.
• For additional entry criteria please refer to the protocol.