Development of pneumococcal vaccines over the last 10 years.

INTRODUCTION: Although significant improvements in the prevention of pneumococcal infections have been achieved in recent years, Streptococcus pneumoniae remains a leading cause of morbidity and mortality. To prevent S. pneumoniae infections, vaccines have been developed for several years. AREAS COVERED: In this review, the most important emerging problems regarding pneumococcal conjugate vaccines (PCVs) are discussed in addition to the status of new vaccine design and development. Given the medical, social and economic relevance of pneumococcal diseases, the availability of effective and safe vaccines against S. pneumoniae is a key objective of public health. EXPERT OPINION: Protein vaccines using agents different from capsular polysaccharides (CPs) or whole-cell vaccines seem to induce a broader immune response than PCVs and theoretically offer definitive solutions, as they can stimulate both humoral and cellular immunity. Moreover, these vaccines, particularly the whole-cell vaccine, are simpler to produce and significantly less expensive. However, the development of these preparations is very far from completion. It is highly likely that for a long time, no new safe and effective pneumococcal vaccines will be available. The best formulation of new pneumococcal vaccines has not been established. Consequently, an effort towards the expanded use of the available vaccines has to be made.