Diseases caused by Streptococcus pneumoniae (S. pneumoniae) are a major public health problem worldwide. More than 100 distinct pneumococcal serotypes have been identified throughout the world. S. pneumoniae is the leading cause of community-acquired pneumonia. Pneumococcal resistance to antimicrobials is a serious and rapidly increasing problem worldwide. There are two principal types of pneumococcal vaccines currently in use: pneumococcal polysaccharide vaccine (PPV) and pneumococcal conjugate vaccines (PCV).

Pneumococci are transmitted by direct contact with respiratory secretions from patients and healthy carriers.

Serious pneumococcal infections include pneumonia, meningitis and febrile bacteraemia; otitis media, sinusitis and bronchitis are more common but less serious manifestations. Pneumococcal pneumonia is frequently preceded by a viral respiratory tract infection and typically presents abruptly with chills and high fever often followed by productive cough and pleuritic pain.