Streptococcus pneumoniae (Pneumococcus)
Diseases caused by Streptococcus pneumoniae (pneumococcus) constitute a major global public health problem. In 2000, about 14·5 million episodes of serious pneumococcal disease (uncertainty range 11·1–18·0 million) were estimated to occur, resulting in about 826 000 deaths (uncertainty range: 582 000–926 000) in children aged 1–59 months, of which an estimated 91 000 (uncertainty range: 63 000–102 000) were in HIV-positive and 735 000 (uncertainty range:519 000–825 000) in HIV-negative children. Of the deaths in HIV-negative children, over 61% (uncertainty range:449 000 [316 000–501 000]) occurred in ten African and Asian countries.
Streptococcus pneumoniae is a major cause of diseases such as pneumonia, meningitis and sepsis, though each of these disease are also caused by other organisms. In the developed world, serious disease occurs mainly in children below two years of age and in the elderly. In developing countries, the disease is common in children under two years, including newborn infants; rates of the disease in the elderly population are largely unknown. Growing resistance of pneumococcus to conventional antibiotics emphasizes the urgent need for vaccines to control pneumococcal disease.
There are close to 90 known serotypes of pneumococcus, though relatively few of these are responsible for most serious disease due to this organism. Antibody to the capsular polysaccharide confers protection against disease, but this protection is serotype specific. In 2007, WHO recommended the use of pneumococcal vaccines in all countries, urging that the highest priority for introduction be given to countries with high pneumonia and under five mortality rates. This recommendation was based on the high levels of disease burden in developing countries and proven efficacy and safety of the pneumococcal conjugate vaccines. A conjugated vaccine containing 7 serotypes of pneumococcus (7-valent conjugated vaccine or PCV 7) has been available since 2000. In 2009, a vaccine containing 10 serotypes, including types 1 and 5 that are important in developing countries, was WHO prequalified for use. In August 2010, a vaccine containing 13 serotypes (4, 6B, 9V, 14, 18C, 19F, 23F, 1, 5, 7F, 3, 6A and 19A) was WHO prequalified.
Surveillance for laboratory confirmed pneumococcal disease is a useful and important tool for demonstrating disease, monitoring vaccine impact and for managing pneumococcal vaccine programmes. A network of sentinel surveillance sites for invasive pneumococcal disease is being established in all regions, under WHO coordination and many sites have now begun reporting surveillance data (Global Invasive Bacterial Vaccine Preventable Diseases (IB VPD) Information and Surveillance Bulletin, Volume 3, January-June 2010; Global Invasive Bacterial Vaccine Preventable Diseases (IB VPD) Information and Surveillance Bulletin, Volume 2, January-December 2009; Global Invasive Bacterial Vaccine Preventable Diseases (IB VPD) Information and Surveillance Bulletin, Volume 1, January-December 2008).
To maximize the impact of pneumococcal vaccines, high and equitable coverage with vaccine is required. This is turn requires strengthening of immunization systems, with special attention to training of health care workers, and enhancing cold chain and logistics capacity. If these issues are adequately addressed the vaccine may be expected to have a significant impact on child mortality in many developing countries, accelerating progress towards achievement of the 4th Millennium Development Goal to reduce child mortality.
This website provides the latest summary information in a set of slides and reference materials available to WHO about progress with decision-making and implementation of rotavirus vaccine introduction.
*Figures taken from the WHO position paper on pneumococcus (WER Vol.78, 14. Starting p.110)
Last updated: October 2011