 Streptococcus pneumoniae is a cause of worldwide morbidity and mortality. Pneumococcal vaccines have been available since the early 1980s. The vaccine which has been licensed for immunization of children 2 years and adults is a polysaccharide-based vaccine 23PPV consisting of capsule parts of the 23 most frequent serotypes of pneumococci. This vaccine elicits in normal immunocompetent persons a high antibody response, which lasts for approximately 10 years. Because the 23PPV is a polysaccharide-based vaccine, it induces a T-cell independent response with no memory and there-fore with no possibility of boosting. In 2001, the first generation of conjugate pneumococcal vaccines PCV7 was licensed. In the PCVs, the capsule material from the pneumococci has been conjugated to a protein, which means that the vaccines can elicit a T-cell dependent immune response even in infants giving memory response and booster possibility. This vaccine has been licensed for use in children from 0-5 years, but studies suggest that PCV immunization might be useful in other groups of people as well etc. immunodeficient children and adults especially now where the second-generation vaccines PCV10, PCV13 have been licensed covering more pneumococcal serotypes. 