Comparative trial of the safety and immunogenicity of quadrivalent (A, C, Y, W-135) meningococcal polysaccharide-diphtheria conjugate vaccine versus quadrivalent polysaccharicle vaccine in two- to ten-year-old children

Background: A quadrivalent meningococcal diphtheria conjugate vaccine (MCV-4) has been developed to provide T-cell dependent immune responses against 4 major disease-causing serogroups (A, C, Y, W-135). Methods: In a comparative, randomized, modified double blind, controlled study in healthy 2- to 10-year-old U.S. children, safety and immunogenicity profiles of MCV-4 (n = 696) were compared with those of a licensed quadrivalent polysaccharide vaccine, Menomune A/C/Y/W-135 (PSV-4, n = 702). Vaccine-related adverse reactions were assessed for 28-day and 6-month follow-tip periods. Serum bactericidal activity (SBA) was assayed in prevaccination, day 28 and 6-month postvaccination sera samples. Results: Both vaccines were well-tolerated, with no vaccine-related serious adverse events and similar rates of mostly mild local and systemic reactions. Functional antibody (SBA) seroconversion percentages were significantly higher for all 4 serogroups in the MCV-4 group. The SBA geometric mean titers against serogroups A, C Y and W-135 with MCV-4 were 1700, 354, 637 and 750, respectively, compared with PSV-4 (893, 231. 408 and 426) 28 days postvaccination (P < 0.001 for all comparisons). This significant difference persisted through 6 months. Conclusions: In 2- to 10-year-old children MCV-4 had a safety profile similar to that of PSV4 and elicited significantly higher and more persistent serum bactericidal antibody responses against meningococcal sero-groups A, C, Y and W-135 than did the licensed polysaccharide vaccine.