ABSTRACT: Meningococcal serogroups A and C cause significant numbers of cases in China. The Sanofi Pasteur meningococcal polysaccharide A + C vaccine (Men-AC) was licensed in China in 1995. Immunogenicity and safety of a single dose of Men-AC against a similar marketed vaccine, the Lanzhou Institute serogroups A and C vaccine (Lanzhou-AC), were evaluated in children 2 to 6 y of age. Antibody titers were determined before and on Day 30 after vaccination using a serum bactericidal assay using baby rabbit complement (SBA-BR). Immunogenicity endpoints included rates of seroconversion (postvaccination antibody titers ≥4-fold higher) and seroprotection (postvaccination titers ≥1:8). Unsolicited systemic adverse events (AEs) within 30 minutes after vaccination, solicited injection site and systemic reactions between Days 0 and 7, unsolicited non-serious AEs within 30 d, and serious adverse events (SAEs) throughout were recorded. Seroconversion rates against serogroups A and C were 97.0% (95% confidence interval [CI], 94.5-98.6) and 94.7% (95% CI, 91.6-97.0), respectively, in the Men-AC group and 97.7% (95% CI, 95.4-99.1) and 94.8% (95% CI, 91.7-97.0), respectively, in the Lanzhou-AC group, while seroprotection rates were 98.0% (95% CI, 95.8-99.3) and 97.0% (95% CI, 94.5-98.6), respectively, in the Men-AC group and 99.0% (95% CI, 97.2-99.8) and 96.8% (95% CI, 94.1-98.4), respectively, in the Lanzhou-AC group. Non-inferiority of Men-AC with regard to immunogenicity was demonstrated since the lower bounds of the 95% CIs of the differences in rates between the two groups were > -5% for both serogroups. Both vaccines were well tolerated.
