RESUMO
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