Pneumococcal vaccines and the prevention of community-acquired pneumonia.

Community-acquired pneumonia (CAP) is a disease that frequently affects children and adults throughout the world. As it places a considerable burden on society and, particularly, healthcare resources, any means of reducing its incidence and impact arouses great interest. A substantial number of paediatric and adult CAP cases are due to Streptococcus pneumoniae but, fortunately, there are effective vaccines available that are likely to have a significant impact on CAP-related medical, social and economic problems. The main aim of this paper is to evaluate the published evidence concerning the impact of pneumococcal vaccines on CAP in children and adults. The original 7-valent pneumococcal conjugate vaccine (PCV-7) completely modified the total burden of pneumococcal diseases in vaccinated children and unvaccinated contacts of any age. However, the existence of some problems moderately reducing its preventive efficacy has led to the development of PCVs with a larger number of pneumococcal serotypes, including those that were previously of marginal importance but now cause of severe disease. It is reasonable to think that these PCVs (particularly PCV13, which includes all of the most important serotypes emerging since the introduction of PCV7) will further reduce the importance of pneumococcal diseases, although it is still not clear whether the replacement of the 23-valent polysaccharide vaccine with PCV13 would be more protective in adults.