Immunogenicity of a single dose of tetravalent meningococcal serogroups A, C, W-135, and Y conjugate vaccine administered to 2- to 10-year-olds is noninferior to a licensed-ACWY polysaccharide vaccine with an acceptable safety profile.

Background: Meningococcal disease remains an important cause of invasive bacterial infections in children less than 5 years of age. Immunogenicity and safety of the investigational ACWY vaccine conjugated with tetanus toxoid (ACWY-TT, GlaxoSmithKline Biologicals) were evaluated in 1501 healthy 2- to 10-year-old children in the Philippines, India, Lebanon, and Saudi Arabia. Methods: Children were randomized (3:1) to receive ACWY-TT or licensed tetravalent meningococcal polysaccharide vaccine (Mencevax, GlaxoSmithKline, Men-PS). Diary cards were used to collect solicited symptoms for 4 days after vaccination. Serious adverse events were reported for 6 months. Serum bactericidal activity (rSBA, rabbit complement) was measured before and 1 month after vaccination in the first 75% of subjects enrolled in each country. Results: The statistical criteria for noninferiority in terms of rSBA vaccine responses were reached. Exploratory analyses showed that postvaccination rSBA titers >= 1:8 and >= 1:128 were significantly higher after ACWY-TT than Men-PS for serogroups C, W-135, and Y, and rSBA vaccine responses and geometric mean antibody titers were significantly higher for all 4 serogroups after administration of ACWY-TT. Noninferiority in terms of incidences of grade 3 general symptoms was not demonstrated. ACWY-TT was well tolerated with grade 3 events reported in <1% of subjects per group. No serious adverse events were considered related to vaccination. Conclusion: ACWY-TT was immunogenic in children between 2 to 10 years of age with a clinically acceptable safety profile that resembled licensed Men-PS. These data support a positive benefit/risk ratio for the ACWY-TT vaccine.