Impact of meningococcal vaccination with combined serogroups A and C polysaccharide vaccine on carriage of Neisseria meningitidis C

Abstract

Two studies of meningococcal carriage state were carried out in Galicia (Spain) before and after a mass vaccination campaign between December 1996 and January 1997 against Neisseria meningitidis serogroup C with meningococcal serogroups A and C polysaccharide vaccine. The studies covered two areas with different incidence rates of meningococcal disease in 1996 (high and low incidence). Carriage rates of serogroup C showed a decrease in both areas, 47 and 65 % respectively, before and after the vaccination. Results showed a decrease in carrier state in the age groups 10-14-and 15-19-year-olds, but not in the 5-9-year-olds. These results demonstrate the effect of immunization on the reduction of the carriage state. INTRODUCTIONIn Galicia, a region situated in north-west Spain (population, 2·7 million), meningococcal disease is an endemic disease. During the early part of the 1990s, the approximate incidence rate of meningococcal disease was three cases per 100 000 population, but by 1995/1996, the incidence had risen sharply to 11 cases per 100 000 population. Unlike previous years, when Neisseria meningitidis serogroup B was the most frequently isolated serogroup, the increased incidence registered in 1995/1996 was caused by N. meningitidis serogroup C (Direcció n Xeral de Saú de, 1995). Faced with this situation, the Galician Regional Public Health Authorities looked into different disease prevention and control measures, and eventually decided to conduct a N. meningitidis C vaccination campaign, using meningococcal group A and C polysaccharide vaccine and targeting all residents in Galicia aged 18 months to 19 years. The campaign was carried out in the period December 1996-January 1997, with a total of 472 465 vaccinated persons.In the wake of the vaccination campaign, a marked decline in the incidence of meningococcal disease was observed. By 1998, 1 year after vaccination, the incidence rate had declined from a pre-vaccination figure of 10·42 to 4·3 cases per 100 000 population (Direcció n Xeral de Saú de, 1998). At this time, it was decided that, in view of the importance of healthy carriers in the epidemiology of meningococcal disease (Broome, 1986), a study should be undertaken immediately prior to vaccination, aimed at ascertaining the incidence of carriers of N. meningitidis C : 2b : P1.2.5 -the strain most frequently isolated during the epidemic period -and studying the relationship between carriage and incidence of meningococcal disease (Fernández et al., 1999). For study purposes, two areas that registered different meningococcal disease incidence were therefore demarcated.In 1998, 1 year after the vaccination campaign, a new N. meningitidis C carriage study was carried out, with the aim of determining any possible differences in carriage prevalence before and after vaccination with meningococcal group A and C polysaccharide vaccine. This paper reports the differences between the above two studies, which covered the segment of the population aged 5-19 years. METHODSPopulation and selection of sample. ...

Development of Immunity to Serogroup B Meningococci during Carriage of Neisseria meningitidis in a Cohort of University Students

“…Although the numbers are small, the level of carriage of serogroup C meningococci (5%; n ϭ 2) was comparable to the equivalent population at the time of the outbreak (7). These results are consistent with observations that immunization with capsular polysaccharide alone may not eliminate carriage of the corresponding meningococcal serogroup (12,6). Carriage of serogroup B meningococci was significantly higher than carriage of serogroup C, with colonization detected in 14% (n ϭ 6) of individuals at some point in the study.…”

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

“…All showed a higher overall carriage rate in vaccinees than controls (only two statistically significant); one reported a lower carriage rate of serogroup C meningococci 1 year post‐vaccination in vaccinees (Aceitero 2000). A before‐and‐after study of a mass group A + C polysaccharide vaccination campaign conducted in Spain (Fernandez et al. 2003) found a significant reduction in carriage of serogroup C strains in vaccinated children living in a high‐incidence area but not in children living in a low‐incidence area.…”

“…Twelve studies involved controlled trials (Gotschlich et al 1969;Artenstein et al 1970;Devine et al 1970;Wenzel et al 1973;Makela et al 1975;Wahdan et al 1977;Greenwood et al 1978;Sivonen 1981;Blakebrough et al 1983;Bjune 1992;Boslego et al 1995;Perkins et al 1998), 10 studies evaluated carriage preand post-vaccination (Bosmans et al 1980;Masterton et al 1988;Dimartino et al 1990;Stroffolini et al 1990;Maiden et al 2002;Fernandez et al 2003;Djibo et al 2004;Eslami-Nejad et al 2005;Caugant et al 2006;Mueller et al 2006) and seven were cross-sectional surveys carried out post-vaccination (Hassan-King et al 1988;Neal et al 1998;Smith et al 1999;Aceitero 2000;Cardenosa et al 2001;Dominguez et al 2001;Pavlopoulou et al 2004).…”

Neisseria meningitidis: an overview of the carriage state

“…The study demonstrated a decrease of carriage rate of serogroup C 1 year after vaccination. The decline in prevalence of N. meningitidis serogroup C was especially considerable in 10-14-and 15-19-year-olds, but not in the 5-9-year-olds (Fernandez et al, 2003). Culturing of nasopharyngeal swabs, 3 weeks after vaccination with the polysaccharide A/C vaccine in the training centre for army medical officers in Italy, revealed that the percentage of isolates belonging to serogroup C was significantly reduced from 6 to 0 .…”