Despite good access to effective antibiotics, Streptococcus pneumoniae (pneumococci) is still a major cause of disease and death in both developing and developed countries. Pneumococci are the main cause of bacterial respiratory tract infections, such as pneumonia, middle ear infection, and sinusitis, in all age groups. The youngest and the elderly are those most prone to invasive pneumococcal infections, such as severe blood infection, meningitis and pneumonia. Carriage of pneumococci without symptoms in the nose of young children is common.
An older generation of pneumococcal vaccines (polysaccharide vaccines) are registered throughout the world. They protect against invasive pneumococcal disease in adults. Such vaccines, instead, have little effect in children under five years of age and do not prevent the carriage without symptoms.
A new generation of (conjugated) vaccines appears to be highly efficient against invasive disease and it also prevents nasopharyngeal carriage. These vaccines cover the types of the bacteria commonly seen in childhood invasive disease and also those associated with antimicrobial resistance.