Long-term Effects of Pneumococcal Conjugate Vaccine on Nasopharyngeal Carriage of S. Pneumoniae, S. Aureus, H. Influenzae and M. Catarrhalis

PLoS One. 2012;7(6):e39730. doi: 10.1371/journal.pone.0039730. Epub 2012 Jun 25.

Abstract

Background: Shifts in pneumococcal serotypes following introduction of 7-valent pneumococcal conjugate vaccine (PCV-7) may alter the presence of other bacterial pathogens co-inhabiting the same nasopharyngeal niche.

Methodology/principal findings: Nasopharyngeal prevalence rates of S. pneumoniae, S. aureus, H. influenzae and M. catarrhalis were investigated before, 3 and 4.5 years after introduction of PCV-7 in the national immunisation program in children at 11 and 24 months of age, and parents of 24-month-old children (n≈330/group) using conventional culture methods. Despite a virtual disappearance of PCV-7 serotypes over time, similar overall pneumococcal rates were observed in all age groups, except for a significant reduction in the 11-month-old group (adjusted Odds Ratio after 4.5 years 0.48, 95% Confidence Interval 0.34-0.67). Before, 3 and 4.5 years after PCV-7 implementation, prevalence rates of S. aureus were 5%, 9% and 14% at 11 months of age (3.59, 1.90-6.79) and 20%, 32% and 34% in parents (1.96, 1.36-2.83), but remained similar at 24 months of age, respectively. Prevalence rates of H. influenzae were 46%, 65% and 65% at 11 months (2.22, 1.58-3.13), 52%, 73% and 76% at 24 months of age (2.68, 1.88-3.82) and 23%, 30% and 40% in parents (2.26, 1.58-3.33), respectively. No consistent changes in M. catarrhalis carriage rates were observed over time.

Conclusions/significance: In addition to large shifts in pneumococcal serotypes, persistently higher nasopharyngeal prevalence rates of S. aureus and H. influenzae were observed among young children and their parents after PCV-7 implementation. These findings may have implications for disease incidence and antibiotic treatment in the post-PCV era.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Carrier State
  • Child, Preschool
  • Cross-Sectional Studies
  • Female
  • Haemophilus influenzae / isolation & purification*
  • Humans
  • Infant
  • Male
  • Moraxella catarrhalis / isolation & purification*
  • Nasopharynx / microbiology*
  • Pneumococcal Vaccines / therapeutic use*
  • Staphylococcus aureus / isolation & purification*
  • Streptococcus pneumoniae / isolation & purification*

Substances

  • Pneumococcal Vaccines