Implementation and impact of a meningococcal C con

Authors: Elena Rego Romero Victoria Nartallo Penas José Antonio Taboada Rodríguez Alberto Malvar Pintos Xurxo Hervada Vidal María José López Pimentel

Publish Date: 2011/03/16

Volume: 19, Issue: 5, Pages: 409-415

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Abstract

In response to increased case numbers of meningococcal group C disease catchup vaccination strategies have been shown to be successful This paper describes the results of a repeat vaccination program in Galicia Spain and the strategy used for itThree vaccination waves were performed first in 1996/1997 with a meningococcal group A and C polysaccharide vaccine in individuals aged 18 months to 19 years second in 2000 with a conjugate serogroup C polysaccharide vaccine in children born since 1993 and all children and adolescents up to 19 years not previously vaccinated third a campaign in 2006 that became necessary because of the development of a new Neisseria strain and an increase in both the incidence and lethality of meningococcal C disease The conjugate vaccine deOacetylated group C meningococcal polysaccharide coupled to tetanus toxoid was used GCMPTT brand name NeisVacC Results Applying a strategy based on model calculations derived from the UK setting and focusing on a population aged 13–25 years including students employees of companies and underage individuals a total of 286000 subjects were vaccinated resulting in global vaccination coverage of 822 all age groups over 74 Only 17 adverse events in 17 individuals were reported which all were mild Incidence of meningococcal disease serogroup C by season was reduced from 084 cases per 100000 in 2004/05 to 076 cases per 100000 in 2005/2006 to 018/100000 in 2007/08 In parallel mortality was also decreased from 8 cases during 2005/06 029 per 100000 to 1 case in 2007/2008 003 per 100000 No cases of breakthrough disease occurred in the vaccinated populationIn Galicia a series of vaccination campaigns particularly focusing on highrisk groups has shown high effectiveness with a marked reduction in the disease incidence in the vaccination cohort accompanied by a relevant reduction in the overall populationNeisseria meningitidis is the leading cause of bacterial meningitis and septicemia in children and adolescents It is associated with a high mortality rate of 10–15 and substantial morbidity rate approximately 20 of survivors develop permanent sequelae Rosenstein et al 1999 The implementation of effective vaccination programs is key to controling meningococcal disease Trotter and Ramsay 2007 While at least 13 serologically distinct groups are known the great majority of invasive meningococcal disease is caused by the serotypes A B C W135 and Y with a preponderance of serotype B although serotype C still has an important disease impact in European countries Thus meningococcal conjugate vaccines against only serogroup C are in widespread usePlain meningococcal group A and C polysaccharide vaccines are of limited value for routine immunization They are poorly immunogenic in infants and children under 2 years of age the age group at highest risk of contracting meningococcal disease In addition the immune response induced by these vaccines is rather short lived and revaccination is known to result in immunologic hyporesponsiveness De Wals et al 2001 Granoff et al 1998 World Health Organization 2002 Conjugated polysaccharide vaccines in which the capsular polysaccharide is covalently conjugated to a carrier protein eliciting both B and Tcell responses are highly immunogenic in children younger than 2 years of age and have been shown to induce immunologic memory Borrow and Findlow 2009 Therefore meningococcal conjugate vaccines are suitable for use in routine childhood vaccinationAlso in Galicia—an autonomic administrative region in the northwest of Spain—meningococcal disease is endemic Galicia has a meningitis surveillance system and since 1995 it also has had an active surveillance system based on cases reported on a weekly basis by hospitals Between 1990 and 1995 the incidence rate was about 35 cases per 100000 individuals and thus slightly higher than the average rate in Spain 31 cases/100000 The majority of cases were caused by serogroup B However in 1995/96 the incidence of meningococcal disease rose sharply from 35 to 113 cases per 100000 and 83 of cases were caused by serogroup C most frequent strain C2bP125 cluster A4 ST8 BEG 1996 Fatal cases occurred in children and adolescents there was heavy media coverage and considerable social alarm

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