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Related Experiment Video

Updated: Feb 5, 2026

Experimental Human Pneumococcal Carriage

Experimental Human Pneumococcal Carriage

Published on: February 15, 2013

Pneumococcal Vaccines: Host Interactions, Population Dynamics, and Design Principles.

Nicholas J Croucher¹, Alessandra Løchen¹, Stephen D Bentley²

¹Department of Infectious Disease Epidemiology, Imperial College London, London W2 1PG, United Kingdom.

Annual Review of Microbiology

|September 12, 2018

Summary

This summary is machine-generated.

Pneumococcal conjugate vaccines (PCVs) protect infants by reducing vaccine-type carriage and disease, leading to herd immunity. Alternative vaccines aim for broader protection against Streptococcus pneumoniae.

Keywords:

conjugate vaccine herd immunity pneumococcus serotype replacement vaccine

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Area of Science:

Microbiology
Immunology
Vaccinology

Background:

Streptococcus pneumoniae, a common bacterium, causes significant disease, particularly in infants.
Pneumococcal polysaccharide vaccines are ineffective in infants due to T cell-independent responses.
Polysaccharide conjugate vaccines (PCVs) elicit T cell-dependent immunity, reducing nasopharyngeal carriage of vaccine serotypes (VTs) and conferring herd immunity.

Purpose of the Study:

To review the impact of PCVs on Streptococcus pneumoniae carriage and disease.
To discuss the limitations of current PCVs, particularly in infants and adults.
To explore alternative vaccine strategies targeting conserved antigens and innate/cellular immunity.

Main Methods:

Review of existing literature on Streptococcus pneumoniae epidemiology and vaccine impact.
Analysis of immune responses elicited by polysaccharide conjugate vaccines.
Examination of emerging vaccine candidates and their mechanisms of action.

Main Results:

PCVs have significantly reduced infant pneumococcal disease and carriage of VTs.
Herd immunity has been observed following widespread PCV implementation.
Replacement of VTs by non-VTs in carriage has occurred.
Reductions in adult disease are less pronounced due to age-varying serotype invasiveness.
Alternative vaccines show promise in stimulating broader immune responses.

Conclusions:

PCVs have been highly effective in reducing infant pneumococcal disease and carriage.
The shift to non-VTs and age-varying invasiveness necessitates ongoing vaccine development.
Future vaccines targeting conserved antigens and innate/cellular immunity may offer broader, species-wide protection against Streptococcus pneumoniae.