2462. Immunogenicity and Safety of a Quadrivalent Meningococcal Conjugate Vaccine (MenACYW-TT) Administered in Individuals 56 Years of Age and Older

Abstract

BackgroundThe MenACYW-TT conjugate vaccine is a quadrivalent meningococcal vaccine candidate intended for global use in all age groups. This Phase III study evaluated the safety and immunogenicity of the vaccine when compared with a licensed quadrivalent meningococcal polysaccharide vaccine (MPSV4) in adults ≥56 years of age.MethodsA randomized, modified double-blind, multicenter study (NCT02842866) was conducted in 907 healthy adults in the United States. Participants were randomized to receive a single dose of either MenACYW-TT conjugate vaccine or MPSV4, stratified according to age into 2 subsets: 56 to 64 and ≥65 years. Descriptive analyses were also planned for age subsets 65–74 years and ≥75 years. Serum bactericidal assay with human (hSBA) and baby rabbit (rSBA) complement was used to measure antibodies against serogroups A, C, Y, and W test strains at baseline and 30 days after vaccination. Safety data were collected up to six months post-vaccination.ResultsNon-inferiority of immune responses was demonstrated between MenACYW-TT conjugate vaccine and MPSV4 based on percentages of subjects achieving hSBA vaccine seroresponse for serogroups A, C, Y, and W at Day 30 compared with baseline. The proportions of individuals with hSBA ≥ 1:8 obtained after MenACYW-TT conjugate vaccine were higher than those after MPSV4 for all four serogroups (A: 89.4% vs. 84.2%; C: 90.1% vs. 70.9%; W: 77.4% vs. 63.0%; Y: 91.7% vs. 67.7%). Overall, the results were similar in the three age substrata. Percentages of participants with post vaccination rSBA ≥ 1:128 were numerically higher for all serogroups in subjects vaccinated with MenACYW-TT conjugate vaccine. A difference in the local reactogenicity profiles was observed between the two vaccine groups, possibly influenced by the different routes of administration. Most unsolicited adverse events were of Grade 1 or Grade 2 intensity. No vaccine related serious adverse events were reported.ConclusionMenACYW conjugate vaccine was immunogenic and well tolerated when administered to individuals ≥56 years of age. Such a vaccine will offer an alternative for the prevention of invasive meningococcal disease in areas of the world where only polysaccharide vaccines are currently available for immunization of older adults.Disclosures A. Esteves-Jaramillo, Sanofi Pasteur: Employee, Educational support and Salary. D. Neveu, Sanofi Pasteur: Employee, Salary. M. S. Dhingra, Sanofi Pasteur: Employee, Educational support and Salary.