Focus on pneumococcal vaccines and nasopharyngeal carriage

Abstract

The vaccination is the only available tool to prevent disease caused by Streptococcus pneumoniae. In this review emphasiswas given on pneumococcal conjugate vaccine (PCV) and S. pneumoniae nasopharyngeal carriage, as nasopharynx colonizationprecede invasive disease. To optimize the development of future conjugate vaccines and to evaluate their efficacy, it isnecessary to understand the serogroup specific epidemiology of pneumococci and their associated disease types.Continuous monitoring of S. pneumoniae serotypes is essential since it has been shown that the incidence of types responsiblefor invasive disease can change over time. The extended protection increases the cost effectiveness of PCV and shouldclearly encourage its use in poorly resourced countries. However, the accumulated experience also shows that the herdimmunity, due to PCV, is partly offset by replacement of the vaccine serotypes by other, nonvaccine serotypes. Owing to thegeneral reduced virulence of the latter, this has only had a modest effect on disease, but the possibility of more virulentnonvaccine serotypes arising cannot be ignored and should be the focus of continued surveillance