Streptococcus pneumoniae epidemiology, pathogenesis and control.

Infections caused by Streptococcus pneumoniae (also known as pneumococci) pose a threat to human health. Pneumococcal infections are the most common cause of milder respiratory tract infections, such as otitis and sinusitis, and of more severe diseases, including pneumonia (with or without septicaemia) and meningitis. The introduction of pneumococcal conjugate vaccines in the childhood vaccination programme in many countries has led to a notable decrease of severe invasive pneumococcal disease in vaccinated children. However, infections caused by non-vaccine types have concurrently increased, causing invasive pneumococcal disease in unvaccinated populations (such as older adults), which has hampered the effect of these vaccines. Moreover, emerging antibiotic resistance is threatening effective therapy. Thus, new approaches are needed for the treatment and prevention of pneumococcal infections, and recent advances in the field may pave the way for new strategies. Recently, several important findings have been gained regarding pneumococcal epidemiology, genomics and the effect of the introduction of pneumococcal conjugate vaccines and of the COVID-19 pandemic. Moreover, elucidative pathogenesis studies have shown that the interactions between pneumococcal virulence factors and host receptors may be exploited for new therapies, and new vaccine candidates have been suggested. In this Review, we summarize some recent findings from clinical disease to basic pathogenesis studies that may be of importance for future control strategies.