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Updated: Jun 7, 2026
Capsular Serotyping of Streptococcus pneumoniae by Latex Agglutination
Published on: September 25, 2014
Systematic evaluation of serotypes causing invasive pneumococcal disease among children under five: the pneumococcal
Hope L Johnson1, Maria Deloria-Knoll, Orin S Levine
1International Vaccine Access Center, Department of International Health, Johns Hopkins University Bloomberg School of Public Health, Baltimore, Maryland, United States of America. hjohnson@jhsph.edu
Insights
A few key pneumococcal serotypes cause the majority of invasive pneumococcal disease (IPD) deaths in children globally. Existing vaccines cover serotypes responsible for millions of cases and hundreds of thousands of deaths, particularly in developing nations.
Area of Science:
- Epidemiology
- Vaccinology
- Global Health
Background:
- Pneumococcal disease causes approximately 800,000 child deaths annually, predominantly in developing countries.
- Limited access to serotype-based vaccines exacerbates the burden of pneumococcal disease in vulnerable populations.
- Understanding the global distribution of pneumococcal serotypes is crucial for targeted vaccine development and policy.
Purpose of the Study:
- To systematically estimate the global and regional distribution of pneumococcal serotypes causing invasive pneumococcal disease (IPD) in children under 5 years of age.
Main Methods:
- Systematic review of published and unpublished studies on IPD serotype data in children under 5.
- Inclusion of studies with at least 12 months of surveillance and reporting at least 20 serotyped isolates, conducted before 2007.
- Random effects meta-analysis of serotype-specific proportions, combined with incidence and mortality data to estimate disease burden.
Main Results:
- 169 studies from 70 countries, comprising 60,090 isolates, were included in the analysis.
- A limited number of serotypes (6-11) accounted for over 70% of IPD cases globally and regionally.
- Seven specific serotypes (1, 5, 6A, 6B, 14, 19F, 23F) were most common globally, causing over 300,000 deaths in Africa and 200,000 in Asia (based on year 2000 estimates).
- Serotypes included in 10- and 13-valent pneumococcal conjugate vaccines (PCVs) were associated with 10 million cases and 600,000 deaths worldwide.
Conclusions:
- A small group of pneumococcal serotypes are responsible for the majority of invasive pneumococcal disease worldwide.
- Existing pneumococcal conjugate vaccine (PCV) formulations cover serotypes that cause a significant proportion of IPD deaths in high-burden regions like Africa and Asia.
- Despite the high disease burden and vaccine-preventable deaths, access to these life-saving vaccines remains limited in many developing countries.
Background:
Approximately 800,000 children die each year due to pneumococcal disease and >90% of these deaths occur in developing countries where few children have access to life-saving serotype-based vaccines. Understanding the serotype epidemiology of invasive pneumococcal disease (IPD) among children is necessary for vaccine development and introduction policies. The aim of this study was to systematically estimate the global and regional distributions of serotypes causing IPD in children <5 years of age.
Methods And Findings:
We systematically reviewed studies with IPD serotype data among children <5 years of age from the published literature and unpublished data provided by researchers. Studies conducted prior to pneumococcal conjugate vaccine (PCV) introduction, from 1980 to 2007, with ≥12 months of surveillance, and reporting ≥20 serotyped isolates were included. Serotype-specific proportions were pooled in a random effects meta-analysis and combined with PD incidence and mortality estimates to infer global and regional serotype-specific PD burden. Of 1,292, studies reviewed, 169 were included comprising 60,090 isolates from 70 countries. Globally and regionally, six to 11 serotypes accounted for ≥70% of IPD. Seven serotypes (1, 5, 6A, 6B, 14, 19F, 23F) were the most common globally; and based on year 2000 incidence and mortality estimates these seven serotypes accounted for >300,000 deaths in Africa and 200,000 deaths in Asia. Serotypes included in both the 10- and 13-valent PCVs accounted for 10 million cases and 600,000 deaths worldwide.
Conclusions:
A limited number of serotypes cause most IPD worldwide. The serotypes included in existing PCV formulations account for 49%-88% of deaths in Africa and Asia where PD morbidity and mortality are the highest, but few children have access to these life-saving vaccines. Please see later in the article for the Editors' Summary.
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