CONJUGATE MENINGOCOCCAL SEROGROUP-A AND SEROGROUP-C VACCINE - REACTOGENICITY AND IMMUNOGENICITY IN UNITED-KINGDOM INFANTS

The reactogenicity and immunogenicity of a serogroup A and C meningoco ccal polysaccharide-CRM(197) conjugate vaccine was evaluated in 58 inf ants who received three doses at 2, 3, and 4 months of age. The conjug ate vaccine produced few systemic side effects, and local reactions we re significantly less common than those produced by the routine vaccin ations. The prevaccination geometric mean titers (GMTs) of A and C pol ysaccharide antibodies were, respectively, 2.8 and 0.6 mu g/mL, rising to 21.5 and 38.5 mu g/mL by 1 month after the third dose (age 5 month s) and falling to 3.1 and 2.2 mu g/mL by 14 months of age. Prevaccinat ion serum bactericidal titers against 2 serogroup C meningococci strai ns were <1/4 in 49 of 52 infants, rising to a GMT of 1/3082 at 1 month after the third dose and falling by age 14 months to a GMT of 1/10. T hus, this meningococcal conjugate vaccine proved to be safe and immuno genic, inducing high levels of anti -C polysaccharide antibodies that were bactericidal in young infants.