Infection with Streptococcus pneumoniae (pneumococcus) is a leading cause of illness in young children and of illness and death in elderly people and people with immune deficiencies and chronic illness. Pneumococcus causes a spectrum of disease: infections of the upper respiratory tract, otitis media, invasive infections such as bacteraemia and meningitis, and infections of the lower respiratory tract such as pneumonia.w1 Polyvalent pneumococcal polysaccharide vaccines containing more than one capsular antigen of pneumococcus have been around since the 1940s. The current 23-valent pneumococcal polysaccharide vaccine was introduced in the United States in 1983.w2 Its antigenic composition reflects the incidence of the 23 serotypes in the causation of invasive disease, as well as coverage of themost prevalent serotypes.w2 As each of the many pneumococcal serotypes has a different epidemiology and probably invasiveness this combined vaccine has a very broad spectrum.w3 Pneumococcal polysaccharide vaccine is recommended in the United States for use in all people aged 65 years or more and in people at risk aged 2 years …