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Community (Herd) Immunity

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Learn how immunizing a critical portion of a community protects most members of the community from the spread of many contagious diseases.

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Pneumococcal Disease

Streptococcus pneumoniae are bacteria frequently found in the upper respiratory tract of healthy children and adults. These bacteria, however, can also cause a range of infections—from relatively mild ear infections to fatal pneumonia, meningitis, and sepsis. Serious pneumococcal infections can occur throughout life, but children under 2 years old and the elderly are at highest risk.

Serious pneumococcal infections are a major global health problem. The World Health Organization (WHO) estimates that more than 1.6 million people—including more than 800,000 children under 5 years old—die every​ year from pneumococcal infections. Nearly all these deaths occur in the world’s poorest countries. Pneumococcal meningitis is the most severe form of pneumococcal disease and one of the most fatal childhood illnesses. In developing countries, it kills or disables 40 to 70 percent of children who get it.

The primary causes of death from pneumococcus are pneumonia, in which fluid fills the lungs, hindering oxygen from reaching the bloodstream; meningitis, an infection of the fluid surrounding the spinal cord and brain; and sepsis, an overwhelming infection of the bloodstream by toxin-producing bacteria.


Pneumonia can be diagnosed in a number of different ways. A chest X-ray is the most specific way to diagnose pneumonia. Healthcare providers can also diagnose many cases by using a stethoscope and/or observing a child’s respiratory rate and breathing patterns.

Antibiotic Resistance, HIV Worsen Threat

Pneumococcal infections are becoming more difficult to treat as bacteria become resistant to some of the most commonly used antibiotics. Antibiotic resistance has economic as well as clinical consequences. Overuse of antibiotics leads to increased resistance and threatens the effectiveness of existing therapy, which in turn increases the cost of treatment by requiring the use of more expensive antibiotics.


Data from a recently published study suggest that the problem of pneumococcal disease will increase in the wake of increasing HIV infection. Data from a South African study show that children with HIV/AIDS are 20 to 40 times more likely to get pneumococcal disease than children without HIV/AIDS.

Saving Lives With Vaccines

New, lifesaving pneumococcal vaccines are safe and highly effective in preventing pneumococcal disease. Since 2000, when U.S. infants began receiving routine vaccination against pneumococcal disease, the country has nearly eliminated childhood pneumococcal disease caused by vaccine serotypes. In addition, vaccination of infants has reduced the spread of pneumococcal bacteria so that adults have less contact with pneumococci and are thus indirectly protected from pneumococcal disease.

Quick Facts About Pneumococcal Disease and Vaccination

  • According to WHO, pneumococcal pneumonia and meningitis are responsible for 800,000 to 1 million child deaths each year. (1, 2)
  • More than 90 percent of pneumococcal pneumonia deaths in children occur in developing countries. (Derived from 3)
  • In developing countries, pneumococcal meningitis kills or disables 40 to 75 percent of children who get it. (4, 8)
  • Children with HIV/AIDS are 20 to 40 times more likely to get pneumococcal disease than children without HIV/AIDS. (5, 6)
  • Increasing rates of drug-resistant pneumococcal infections threaten the effectiveness of antibiotic treatment. (9, 10, 11)
  • Conjugate pneumococcal vaccination is safe and effective for preventing severe childhood pneumococcal disease caused by serotypes included in the vaccine. (1)
  • Conjugate vaccines containing 7 to 11 pneumococcal serotypes are expected to prevent 50 to 80 percent of all serious childhood pneumococcal disease worldwide. (13)
  • High-risk infants and children, including those with HIV infection, can be safely and effectively vaccinated with pneumococcal conjugate vaccines. (7)
  • Conjugate pneumococcal vaccines represent an effective tool for preventing antibiotic-resistant infections. (1, 12, 14)
  • Routine pneumococcal conjugate vaccination in developing countries could contribute to achieving the United Nations Millennium Development Goal to decrease childhood deaths by two-thirds by the year 2015.



  1. World Health Organization. Pneumococcal vaccines. The Weekly Epidemiological Record. 2003; 14:110-9.
  2. Global Alliance for Vaccines and Immunization. Annual deaths in 2001 from diseases for which vaccines will be available soon WHO estimates (June 2003). [Online]. [Accessed 2005].
  3. Williams BG, Gouws E, Boschi-Pinto C, Bryce J, Dye C. Estimates of world-wide distribution of child deaths from acute respiratory infections. The Lancet Infectious Diseases. 2(1): 25 (2002).
  4. Goetghebuer T et al. Outcome of meningitis caused by Streptococcus pneumoniae and Haemophilus influenzae type b in children in The Gambia. Tropical Medicine and International Health. 5(3): 207 (2000).
  5. Madhi SA, Petersen K, Madhi A, Wasas A, Klugman KP. Impact of human immunodeficiency virus type 1 on the disease spectrum of Streptococcus pneumoniae in South African children. Pediatric Infectious Diseases Journal. 19: 11 (2000).
  6. Mao C et al. Invasive pneumococcal infections in human immunodeficiency virus-infected children. Journal of Infectious Diseases. 173: 870 (1996).
  7. Klugman KP, Madhi SA, Huebner RE, Kohberger R, Mbelle N, Pierce N, Vaccine Trialist Group. A trial of 9-valent pneumococcal conjugate vaccine in children with and those without HIV infection. New England Journal of Medicine. 349: 1341 (2003).
  8. Baraff LJ, Lee SI, Schriger DL. Outcomes of bacterial meningitis in children: a metaanalysis. Pediatric Infectious Diseases Journal. 12: 389 (1993).
  9. Klugman KP. Bacteriological evidence of antibiotic failure in pneumococcal lower respiratory infections. European Respiratory Journal Supplement. 36: 3s (2002).
  10. Dagan R. Clinical significance of resistant organisms in otitis media. Pediatric Infectious Diseases Journal. 19(4): 378 (2000).
  11. American Academy of Pediatrics. Therapy for children with invasive pneumococcal infections. Pediatrics. 99(2): 289 (1997).
  12. Whitney CG et al. Decline in invasive pneumococcal disease after the introduction of protein-polysaccharide conjugate vaccine. New England Journal of Medicine. 348(18): 1737 (2003).
  13. Hausdorff WP. Which pneumococcal serogroups cause the most invasive disease: Implications for conjugate vaccine formulation and use, Part I. Clinical Infectious Diseases. 30: 100 (2000).
  14. Klugman KP. Efficacy of pneumococcal conjugate vaccines and their effect on carriage and antimicrobial resistance. The Lancet Infectious Diseases. 85 (2001).

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Last Updated January 31, 2014