Group C meningococcal polysaccharide-tetanus toxoid conjugate vaccine: a meta-analysis of immunogenicity, safety and posology.

A conjugate vaccine comprised of de-O-acetylated group C meningococcal polysaccharide coupled to tetanus toxoid (GCMP-TT) has been licensed in 32 countries and incorporated in a comprehensive UK vaccination program. Extensive evidence, forming the subject of this meta-analysis, has rapidly accumulated on the immunogenicity, safety and posology of GCMP-TT as well as its epidemiological impact. GCMP-TT has been shown effective after a single dose in individuals >12 months of age, and initial posology specified three doses in infants. However, based on a recent clinical trial, posology was reduced to two doses in infants. Pooled protection rate, defined as proportion of subjects with serum bactericidal antibody (SBA) levels > or = 1:8, was 99.4% (CI, 98.2-99.9%) in seven clinical trials covering all age groups. Robust responses to GCMP-TT have been demonstrated with respect to SBA, IgG levels and antibody avidity. In post-marketing pharmacosurveillance encompassing >12 x 10(6) GCMP-TT doses distributed worldwide, the vaccine has been well tolerated with an incidence rate of 0.01% for all the most commonly encountered types of adverse events. After a catch-up UK vaccination campaign where 5-8 year old children were primarily given GCMP-TT, a 93% decline in meningococcal disease incidence was observed. In view of its immunogenicity, safety and potential suitability for use among infants in reduced dose schedules, GCMP-TT appears to mark a major advance over predecessor polysaccharide vaccines for the prevention of meningococcal C disease.