Pneumococcal conjugated vaccines: impact of PCV-7 and new achievements in the postvaccine era

Abstract

Pneumococcal disease is a major health problem worldwide. Large, rapid declines in overall invasive pneumococcal disease and mucosal disease in children, reductions in vaccine-type disease in unvaccinated children and adults (indirect effects) and significant drops in antibiotic-resistant infections were observed after the introduction of a safe, available and immunogenic seven-valent pneumococcal vaccine. The determination of vaccine efficacy is a complex process, which includes efficacy, immunogenicity, safety, cross-reactivity, indirect effects and substantial geographic variation in serotype coverage. In this report, we perform an overview of the literature on current, investigational and potential candidate pneumococcal conjugated vaccines (PCVs). Every country should have its own strong and sustained surveillance system implemented to monitor the effects of vaccination on the frequency of vaccine and nonvaccine serotypes for invasive or mucosal disease, nasopharyngeal carriage and the indirect effects before and after introduction of PCV. New PCVs (PHiD-CV and PCV-13) may provide even greater coverage worldwide, especially in developing countries. Vaccine experts' efforts are currently focused on developing alternative vaccine strategies against pneumococcal infections, especially the development of vaccines based on pneumococcal proteins.