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Continued impact of pneumococcal conjugate vaccine on carriage in young children

Susan S Huang1, Virginia L Hinrichsen, Abbie E Stevenson

  • 1Division of Infectious Diseases, School of Medicine, University of California, Irvine, Orange, CA 92868, USA. sshuang@partners.org

Pediatrics
|July 1, 2009
PubMed

Insights

The heptavalent pneumococcal conjugate vaccine (PCV7) led to a decrease in vaccine-type Streptococcus pneumoniae carriage in children. Non-vaccine serotypes, particularly 19A and 35B, rapidly replaced them, showing increased penicillin resistance.

Area of Science:

  • Pediatric Infectious Diseases
  • Microbiology
  • Vaccinology

Background:

  • The heptavalent pneumococcal conjugate vaccine (PCV7) was introduced to reduce invasive pneumococcal disease.
  • Understanding serotype and antibiotic resistance shifts in Streptococcus pneumoniae carriage is crucial for public health.
  • The impact of PCV7 on carriage dynamics and risk factors in young children requires ongoing assessment.

Purpose of the Study:

  • To assess serial changes in Streptococcus pneumoniae serotypes and antibiotic resistance in young children.
  • To evaluate if PCV7 altered the risk factors associated with pneumococcal carriage.

Main Methods:

  • Nasopharyngeal specimens were collected from children aged 3 months to <7 years across multiple winter seasons (2000-2007).
  • Antimicrobial susceptibility testing and serotyping were performed on collected Streptococcus pneumoniae isolates.
  • Questionnaire and medical record data were analyzed to identify carriage risk factors.

Main Results:

  • Carriage of non-PCV7 serotypes significantly increased from 15% to 29% between 2000-2001 and 2006-2007.
  • Vaccine serotypes decreased to 3% of carried serotypes by 2006-2007, with serotype 19A becoming highly prevalent.
  • Penicillin nonsusceptibility was noted in high-prevalence serotypes, and traditional carriage predictors persisted.

Conclusions:

  • PCV7 led to the near disappearance of vaccine serotypes in pediatric Streptococcus pneumoniae carriage.
  • Penicillin-nonsusceptible nonvaccine serotypes, especially 19A and 35B, rapidly replaced vaccine types.
  • Established risk factors for pneumococcal carriage, such as childcare attendance, remained unchanged by the vaccine.
Abstract

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