Pneumococcal vaccination in adults: rationale, state of the art and perspectives.

Streptococcus pneumoniae (SP) is a leading cause of morbidity and mortality worldwide. Despite the availability, since the early 1980s, of a 23-valent pneumococcal polysaccharide vaccine (PP V23), its recommendation and increased use in the last decades, and the indirect benefits against invasive pneumococcal diseases following the pediatric immunization strategies with the 7-valent pneumococcal conjugate vaccine (PCV7), pneumoccal diseases, particularly Community Acquired Pneumonia (CAP), still remain a substantial burden among older adults in Western countries. The recent availability on the market of a second generation of pneumococcal conjugate vaccines, with an enlarged spectrum of protection against some serotypes not included in the PCV7 (i.e., the 13-valent pneumococcal conjugate vaccine--PCV13), opens new interesting perspectives for improving the control of this significant health-care issue among the entire population. The most interesting and up-dated epidemiological data regarding the impact of SP in adults and the elderly in Western countries, together with the available evidence concerning the efficacy and effectiveness of the PPV23 in the same population, are reported and discussed below.