Comparative trial of the safety and immunogenicity of quadrivalent (A, C, Y, W-135) meningococcal polysaccharide-diphtheria conjugate vaccine versus quadrivalent polysaccharide 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-up 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 PSV-4 and elicited significantly higher and more persistent serum bactericidal antibody responses against meningococcal serogroups A, C, Y and W-135 than did the licensed polysaccharide vaccine.

Assignment of Neisseria meningitidis serogroups A, C, W135, and Y anticapsular total immunoglobulin G (IgG), IgG1, and IgG2 concentrations to reference sera.

Meningococcal serogroup-specific immunoglobulin G (IgG), IgG1, and IgG2 concentrations were assigned to three reference sera, CDC 1992, 89-SF, and 96/562, for meningococcal serogroups A, C, Y, and W135 via the method of cross standardization. The sum of the serogroup-specific IgG1 and IgG2 concentrations determined for the four meningococcal serogroups showed good agreement with the serogroup-specific IgG either determined here or as previously represented. Following the assignment of meningococcal serogroup-specific IgG1 and IgG2 concentration to these reference sera, a meningococcal serogroup-specific IgG1 and IgG2 enzyme-linked immunosorbent assay protocol was developed. The serogroup A and C specific subclass distribution of a panel of adult sera collected following vaccination with any combination of meningococcal serogroup C conjugate, bivalent, or tetravalent polysaccharide vaccines was determined. For the determination of serogroup W135 and Y specific subclass distribution, an adolescent panel 28 days following a single dose of either tetravalent polysaccharide or conjugate vaccine was used. The sum of the serogroup-specific IgG1 and IgG2 showed strong correlation with the serogroup-specific total IgG determined. The assignment here of IgG1 and IgG2 subclasses to these reference sera will allow more detailed evaluation of meningococcal conjugate and polysaccharide vaccines.

Immunogenicity and immunological priming of the serogroup a portion of a bivalent meningococcal A/C conjugate vaccine in 2-year-old children.

Two-year-old children were vaccinated with 1 dose of meningococcal A/C conjugate (MACC) or meningococcal A/C polysaccharide (MACP) vaccine. Meningococcal serogroup A (MenA)-specific IgG geometric mean avidity indices (GMAIs) increased 1 month after vaccination with MACC (GMAI, 210; 95% confidence interval [CI], 140-300) and MACP (GMAI, 190; 95% CI, 120-310). One year after vaccination, the GMAI of the MACP-vaccinated cohort decreased to 130 (95%, CI 100-170), but a constant GMAI was maintained in the MACC-vaccinated cohort (210; 95% CI, 140-300), despite declining MenA-specific IgG antibody levels.