Cochrane review: Conjugate vaccines for preventing meningococcal C meningitis and septicaemia
Authors: Conterno LO , Silva Filho CR , Rüggeberg JU , Heath PT 
Published: April 2007

AbstractBackgroundMeningococcal polysaccharide (MPLS) vaccines protect against Serogroup C disease, but do not produce an immune response in infants less than two years of age. This limitation can be overcome by linking C polysaccharide to carrier proteins (‘conjugating’), to create meningococcal serogroup C conjugate (MCC) vaccines. In the absence of trial data, the immune response to vaccination has been considered to be a reasonable surrogate for vaccine protection.ObjectivesTo assess the immunogenicity, safety and efficacy of MCC vaccines for preventing meningitis and septicaemia.Search strategyWe searched the Cochrane Central Register Controlled Trials (CENTRAL) (The Cochrane Library Issue 3, 2005); MEDLINE (1966 to September, Week 1 2005); and EMBASE (1990 to June 2005) and references of studies.Selection criteriaRandomised controlled trials (RCTs) and controlled clinical trials (CCTs) in humans comparing MCC vaccines against a control vaccine or none. In the absence of any trials on vaccine efficacy, population‐based observational studies about effectiveness were included.Data collection and analysisTwo authors independently screened the results of the literature searches, selected eligible studies, extracted the data and evaluated the quality of them.Main resultsThe studies showed that MCC vaccine was highly immunogenic in infants after two and three doses, in toddlers after one and two doses and in older age groups after one dose. In general higher titres were generated after MCC than after MPLS vaccines. Immunological hypo‐responsiveness seen after repeated doses of MPLS vaccine may be overcome with MCC. Observational studies have documented a significant decline in meningococcal C disease in countries where MCC vaccines have been widely used. The timing of the vaccinations schedules, the specific conjugate used, and the vaccines given concomitantly or combined, may be important.Authors' conclusionsThe MCC vaccine appears to be safe, immunogenic and able to induce immunological memory in all age groups. Observational studies strongly suggest that MCC is clinically effective.Plain language summaryTraditional meningococcal polysaccharide (MPLS) vaccines protect against Serogroup C disease (caused by Neisseria meningitidis), but do not produce an immune response in infants less than two years of ageThis limitation can be overcome by linking C polysaccharide to carrier proteins (‘conjugating’), to create meningococcal serogroup C conjugate (MCC) vaccines. This review looks at MCC vaccines to protect young children against Serogroup C disease. Trials found that MCC induces an immune response against serogroup C in all age groups, but especially younger children for whom the immune response is greater than that of the traditional MPLS. It appears to be safe. Clinical efficacy of MCC could not be assessed from randomised controlled clinical trials (there were none). However, weaker evidence from observational studies showed a decrease in meningococcal C disease and meningococcal C carriage in countries where vaccines have been widely used.