Immunogenicity and Safety of H influenzae Type b–N meningitidis C/Y Conjugate Vaccine in Infants

Abstract

BACKGROUND: Meningococcal disease incidence is highest in children younger than 2 years of age, yet there is no US-licensed vaccine for this age group. A phase III study evaluated the immunogenicity and safety of an investigational Haemophilus influenzae type b (Hib)–Neisseria meningitidis serogroups C and Y-tetanus toxoid conjugate vaccine (HibMenCY). MATERIALS AND METHODS: A total of 4180 infants were randomly assigned to receive the HibMenCY at the ages of 2, 4, 6, and 12 to 15 months or the licensed Hib tetanus toxoid conjugate vaccine (ActHIB) at 2, 4, and 6 months and Hib conjugated to N meningitidis outer membrane protein (PedvaxHIB) at 12 to 15 months. Routinely scheduled vaccines were coadministered. Serum bactericidal activity using human complement and anti–polyribosylribitol phosphate antibodies were assessed in 991 subjects. Local and systemic adverse reactions were recorded for 4 days after each dose. RESULTS: The percentage of HibMenCY recipients with serum bactericidal assay using human complement titers of 1:8 or higher after dose 3 was 98.8% for N meningitidis serogroup C (MenC) and 95.8% for N meningitidis serogroup Y (MenY). After dose 4, the percentages were 98.5% and 98.8%, respectively. The percentage of HibMenCY recipients with postdose 3 anti-polyribosylribitol phosphate antibody levels of ≥1.0 μg/mL was noninferior to that of control (96.3% vs 91.2%). After dose 4, MenC and MenY serum bactericidal assay using human complement antibody titers increased 12-fold over pre–dose 4 levels. Incidence of pain, redness, and swelling at the HibMenCY injection sites tended to be lower than with Hib type b after the first 3 doses and after the fourth dose. Rates of systemic symptoms were similar across groups. CONCLUSIONS: The HibMenCY was immunogenic against MenC and MenY and induced anti–polyribosylribitol phosphate antibody levels noninferior to those of licensed Hib conjugate vaccine. The safety profile of the HibMenCY was clinically acceptable and comparable to Hib conjugate vaccine.