Streptococcus pneumoniae (Pneumococcus)
Introduction
Diseases caused by Streptococcus pneumoniae (the pneumococcus) constitute a major public health problem all over the world. It is estimated that about 700,000 to 1 million children die of pneumococcal disease every year, most of whom are young children in developing countries. In the developed world, children below 2 years of age and elderly persons carry the major disease burden. In developing countries disease is common in children under two years, including newborn infants; rates of disease in the elderly population are largely unknown. Growing resistance of S. pneumoniae to essential antibiotics underlines the urgent need for vaccines to control pneumococcal disease.
A 7-valent conjugate vaccine was licensed and introduced into the routine immunization programme of the Unites States in 2000. Since then a dramatic decline in rates of pneumococcal disease have been observed not only in the immunized population but also in the unimmunized through reduced transmission of the organism (herd effect). This vaccine lacks certain serotypes which are important causes of disease in developing countries. Ten-valent and 13-valent vaccines are currently under evaluation. In November 2007, the GAVI Board approved and investment case for GAVI support for introduction of pneumococcal conjugate vaccine in eligible countries. Vaccine introduction in eligible countries may start as early as mid-2008.