Systematic review: Impact of meningococcal vaccination on pharyngeal carriage of meningococci

Abstract

Summaryobjective To investigate the effect of meningococcal vaccines on pharyngeal carriage of meningococci. methods Systematic review. MEDLINE and EMBASE were searched for relevant studies. Controlled trials and observational studies which used comparison groups or compared carriage rates before and after vaccination were included in the review.results Twenty-nine studies satisfied the inclusion criteria. Twenty-five studies reported the effect of a polysaccharide vaccine, one the effect of a serogroup C conjugate vaccine and three the impact of serogroup B outer-membrane vaccines on overall and ⁄ or serogroup-specific meningococcal carriage rates. Ten studies of meningococcal polysaccharide vaccines found reduced serogroup-specific carriage; seven of these focussed on high-risk groups and had a short follow-up period. Only one of five studies of civilian populations in Africa showed a significantly reduced carriage. Many studies had methodological shortcomings. The one study which assessed the effect of a meningococcal conjugate vaccine on carriage showed a significant impact. Three studies of serogroup B outer-membrane protein vaccines showed no effect on carriage.conclusions A few well-designed trials of the impact of meningococcal vaccines on carriage have been undertaken. Such studies should be an essential component of the evaluation of new meningococcal vaccines, particularly those introduced to control epidemic meningococcal disease in Africa.keywords meningococcal meningitis, vaccination, carrier state, herd immunity

Cost-effectiveness of vaccination against meningococcal B among Dutch infants

“…15 However, vaccination against MenB disease would be a third injection at these ages, while a maximum of two injections per consult is currently accepted in the Netherlands. 16 Possible solutions could be the acceptance of three injections at one vaccine consult or additional consultations.…”

“…15 However, herd protection has been observed with MenC vaccination. 20,21 Ignoring herd protection when present can substantially underestimate the impact of vaccination.…”

Controlling serogroup B invasive meningococcal disease: the Canadian perspective

“…The ability of a meningococcal vaccine to provide herd immunity in large part depends on its ability to prevent carriage acquisition [71]. Meningococcal polysaccharide vaccines have demonstrated shortterm herd immunity in military populations but not in open communities [71]. MenC conjugate vaccines have been demonstrated to reduce pharyngeal carriage and produce a herd effect [72,73].…”

“…Herd immunity is defined as the ability of immune individuals in a population to protect nonimmune individuals against infection [69,70]. The ability of a meningococcal vaccine to provide herd immunity in large part depends on its ability to prevent carriage acquisition [71]. Meningococcal polysaccharide vaccines have demonstrated shortterm herd immunity in military populations but not in open communities [71].…”

Meningococcal carriage in the African meningitis belt

“…When reactive vaccination with polysaccharide vaccines has been deployed early in an epidemic, it has saved many lives but it has not reduced the frequency of epidemics because polysaccharide vaccines induce protection of limited duration, especially in children, and have little or no impact on carriage (Dellicour & Greenwood 2007). Polysaccharide/protein conjugate vaccines are likely to be more successful in preventing epidemics because they induce immunological memory and decrease pharyngeal carriage.…”