effect of current meningococcal vaccination on meningococcal carriage among new army recruits

ABSTRACT

The impact of vaccination with the bivalent meningococcal vaccine on meningococcal carriage was studied by examining nasopharyngeal smears from vaccinated and non-vaccinated new military recruits. Initial nasopharyngeal swabs were taken from 120 new military recruits and cultured for N.meningitidis 2 days after their entry to the army. Sixty recruits then received the N.meningitidis group A and C polysaccharide vaccine and the other 60 recruits did not. Follow-up swabs from both groups were cultured for N. meningitides after 2, 6 and 10 weeks. The overall carriage rate for N. meningitides in the 120 recruits was 30 percent 52.7 percent for serogroup A, 19.4 percent for serogroup B, 22.2 percent for serogroup C and 5.5 percent for the autoagglutinable group. In the vaccinated group the overall carriage rate did not change significantly over the follow-up period. However, there was a progressive increase of serogroup B prevalence over the follow-up period [from 23.8 percent initially to 65.2 percent 10 weeks after vaccination] P= 0.01. In the non-vaccinated group, the overall carriage rate increased significantly over the follow-up period [from 25 percent initially to 46.7 percent at 10 weeks]. P= 0.04; the sero group prevalence did not change significantly. The results of this study suggest that meningococcal A and C polysaccharide vaccine may inhibit the nasopharyngeal carriage of group specific meningococcal in new army recruits. This inhibition is, however, offset by an increased prevalence of sero group B meningococcal