The impact of specific and non-specific immunity on the ecology of Streptococcus pneumoniae and the implications for vaccination

Stefan Flasche, W. John Edmunds, Elizabeth Miller, David Goldblatt, Charles Robertson, Choi Yoon Hong

Research output: Contribution to journalArticle

24 Citations (Scopus)
54 Downloads (Pure)

Abstract

More than 90 capsular serotypes of Streptococcus pneumoniae coexist despite
competing for nasopharyngeal carriage and a gradient in fitness. The underlying
mechanisms for this are poorly understood and make assessment of
the likely population impact of vaccination challenging. We use an individual-
based simulation model to generalize widely used deterministic models
for pneumococcal competition and show that in these models short-term
serotype-specific and serotype non-specific immunity could constitute the
mechanism governing between-host competition and coexistence. We find
that non-specific immunity induces between-host competition and that serotype-
specific immunity limits a type’s competitive advantage and allows
stable coexistence of multiple serotypes. Serotypes carried at low prevalence
show high variance in carriage levels, which would result in apparent outbreaks
if they were highly pathogenic. Vaccination against few serotypes can
lead to elimination of the vaccine types and induces replacement by others.
However, in simulations where the elimination of the targeted types is
achieved only by a combination of vaccine effects and the competitive pressure
of the non-vaccine types, a universal vaccine with similar-type-specific effectiveness can fail to eliminate pneumococcal carriage and offers limited herd
immunity. Hence, if vaccine effects are insufficient to control the majority of
serotypes at the same time, then exploiting the competitive pressure by
selective vaccination can help control the most pathogenic serotypes.
Original languageEnglish
Article number20131939
Number of pages9
JournalProceedings of the Royal Society B: Biological Sciences
Volume280
Issue number1771
Early online date2 Oct 2013
DOIs
Publication statusPublished - 2013

Fingerprint

Streptococcus pneumoniae
pneumonia
vaccination
vaccine
Ecology
immunity
Innate Immunity
serotypes
Vaccination
Vaccines
ecology
coexistence
Combined Vaccines
vaccines
simulation
fitness
replacement
Serogroup
Immunity
simulation models

Keywords

  • streptococcus pneumoniae
  • carriage competition
  • coexistence
  • immunity
  • vaccination

Cite this

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abstract = "More than 90 capsular serotypes of Streptococcus pneumoniae coexist despitecompeting for nasopharyngeal carriage and a gradient in fitness. The underlyingmechanisms for this are poorly understood and make assessment ofthe likely population impact of vaccination challenging. We use an individual-based simulation model to generalize widely used deterministic modelsfor pneumococcal competition and show that in these models short-termserotype-specific and serotype non-specific immunity could constitute themechanism governing between-host competition and coexistence. We findthat non-specific immunity induces between-host competition and that serotype-specific immunity limits a type’s competitive advantage and allowsstable coexistence of multiple serotypes. Serotypes carried at low prevalenceshow high variance in carriage levels, which would result in apparent outbreaksif they were highly pathogenic. Vaccination against few serotypes canlead to elimination of the vaccine types and induces replacement by others.However, in simulations where the elimination of the targeted types isachieved only by a combination of vaccine effects and the competitive pressureof the non-vaccine types, a universal vaccine with similar-type-specific effectiveness can fail to eliminate pneumococcal carriage and offers limited herdimmunity. Hence, if vaccine effects are insufficient to control the majority ofserotypes at the same time, then exploiting the competitive pressure byselective vaccination can help control the most pathogenic serotypes.",
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The impact of specific and non-specific immunity on the ecology of Streptococcus pneumoniae and the implications for vaccination. / Flasche, Stefan; Edmunds, W. John; Miller, Elizabeth; Goldblatt, David; Robertson, Charles; Yoon Hong, Choi.

In: Proceedings of the Royal Society B: Biological Sciences , Vol. 280, No. 1771, 20131939, 2013.

Research output: Contribution to journalArticle

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