Poor potential coverage for 7-valent pneumococcal conjugate vaccine, Malawi

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Constructing Mutants in Serotype 1 Streptococcus pneumoniae strain 519/43
06:06

Constructing Mutants in Serotype 1 Streptococcus pneumoniae strain 519/43

Published on: September 11, 2020

Stephen B Gordon1, Stonard Kanyanda, Amanda L Walsh

  • 1Wellcome Trust Research Laboratories, University of Malawi, Liverpool, UK. sgordon@mlw.medcol.mw

Emerging Infectious Diseases
|June 5, 2003
PubMed

Insights

New conjugate vaccines help prevent Streptococcus pneumoniae infections but have limited serogroup coverage. Serogrouping data from Malawi shows a 9-valent vaccine could cover 66% of invasive pediatric isolates.

Area of Science:

  • Medical Microbiology
  • Vaccinology
  • Epidemiology

Background:

  • Streptococcus pneumoniae causes significant childhood and adult morbidity and mortality globally.
  • Pneumococcal conjugate vaccines (PCVs) are effective but limited by serogroup coverage.
  • Malawi faces a substantial burden of invasive pneumococcal disease.

Purpose of the Study:

  • To determine the serogroup distribution of invasive and carried Streptococcus pneumoniae isolates in Malawi.
  • To evaluate the potential impact of existing and next-generation pneumococcal conjugate vaccines in this population.

Main Methods:

  • Collection of nasopharyngeal swabs and blood cultures from children and adults in Malawi.
  • Serotyping of Streptococcus pneumoniae isolates using culture-based methods.
  • Analysis of serotype coverage provided by 7-valent and 9-valent pneumococcal conjugate vaccines.

Main Results:

  • The 7-valent PCV would cover 41% of invasive pediatric isolates and 25% of adult invasive isolates.
  • A 9-valent PCV, including serotypes 1 and 5, demonstrated improved coverage.
  • The 9-valent PCV would cover 66% of invasive pediatric isolates and 55% of adult invasive isolates.

Conclusions:

  • Current pneumococcal conjugate vaccines offer suboptimal protection in Malawi.
  • Expanding vaccine valency, particularly to include serotypes 1 and 5, significantly enhances coverage for invasive pneumococcal disease in Malawian children and adults.
  • These findings support the need for vaccine strategies tailored to local serotype prevalence.

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