Haemophilus influenzae type b–Neisseria meningitidis serogroups C and Y tetanus toxoid conjugate vaccine (HibMenCY) was immunogenic with an acceptable safety profile in two Phase 3 trials

Background: The incidence of meningococcal disease is highest in infants, yet there is currently no licensed vaccine in the US for this age group.

Objectives: To assess the immunogenicity and safety of a four dose series of an investigational HibMenCY vaccine.

Methods: In two Phase 3 studies, 8571 US, Australian and Mexican infants were randomized (3:1) to receive HibMenCY or Hib (ActHIB^®, Sanofi Pasteur) at 2, 4 and 6 months, and HibMenCY or Hib (PedvaxHIB^®, Merck & Co., Inc.) at 12–15 months. Routinely recommended vaccines were co-administered. Immunogenicity was assessed 1 month post-dose-3, pre- and 42 days post-dose-4 in 991 US subjects, using ELISA for anti-PRP antibody and serum bactericidal activity using human complement (hSBA) for N. meningitidis serogroups C and Y. Primary endpoints included anti-PRP ≥1.0 mg/mL and hSBA-MenC/Y ≥1:8. Safety was assessed until 6 months post-dose-4 on pooled  data from the two studies.

Results: Vaccination with HibMenCY was non-inferior to licensed Hib for anti-PRP ≥1.0 mg/mL (post-dose-3, 96.3% versus 91.2% respectively; post-dose-4, 99.2% in both groups). In the group receiving HibMenCY, the percentage of subjects with hSBA-MenC ≥1:8 was 98.8% post-dose-3  and 98.5% post-dose-4. Furthermore,  the percentage of subjects receiving HibMenCY with hSBA-MenY ≥1:8 was 95.8% post-dose-3  and 98.8% post-dose-4. HibMenCY had a similar safety profile to ActHIB^® with respect to adverse events (AEs) and serious AEs reported after doses 1, 2 and 3, and to PedvaxHIB^® with respect to AEs reported up to 6 months post-dose-4. Serious AEs, emergency room visits, rash and new onset chronic disease were reported at a similar rate in both groups.

Conclusions: HibMenCY is as immunogenic as a licensed Hib vaccine and has an acceptable safety profile, potentially adding protection for infants against N. meningitidis serogroups C and Y without the need for additional injections.