The immunogenicity and safety of a Hib-MenAC vaccine: a non-inferiority randomized, observer-blind trial in infants aged 3-5 months

<b>Background</b>: The objective of this study was to evaluate the immunogenicity and safety of the novel combined Haemophilus influenzae type b–Neisseria meningitidis serogroup A and C–tetanus toxoid conjugate vaccine (Hib-MenAC). <b>M</b><b>ethods</b>: We conducted a non-inferiority, randomized, observer-blind, positive control clinical trial in 900 healthy infants aged between 3–5 months in Funing County, Jiangsu Province, China. Participants were randomly allocated, in a ratio of 2:1 (block = 6), to receive experimental combined Hib-MenAC vaccines co-administrated with placebo or the co-administration of licensed Hib vaccine and MenAC vaccine, according to a three-dose immunization schedule. The seroconversion of antibody titer against meningococcal serogroups A, C and Hib was the primary endpoint. <b>Results</b>: The experimental vaccines was non-inferior to the licensed two control vaccines. Participants receiving experimental Hib-MenAC vaccines showed a seroconversion rate of 99.0%, 96.1% and 97.7% for rSBA-MenA, rSBA-MenC and anti-PRP antibodies, respectively. The Hib-MenAC vaccine did not result in an increase in adverse reaction, and no serious adverse event was judged to be related to the vaccination. <b>Conclusions</b>: The novel combined Hib-MenAC conjugate vaccine was safe and highly immunogenic in infants aged between 3 to 5 months.