title: The impact of childhood vaccines on bacterial carriage in the nasopharynx: a longitudinal study.
abstract: BACKGROUND
  There is increasing evidence that childhood vaccines have effects that extend beyond their target disease. The objective of this study was to assess the effects of routine childhood vaccines on bacterial carriage in the nasopharynx.
  
  
  METHODS
  A cohort of children from rural Gambia was recruited at birth and followed up for one year. Nasopharyngeal swabs were taken immediately after birth, every two weeks for the first six months and then every other month. The presence of bacteria in the nasopharynx (Haemophilus influenzae, Streptococcus pneumoniae, Staphylococcus aureus) was compared before and after the administration of DTP-Hib-HepB and measles-yellow fever vaccines.
  
  
  RESULTS
  A total of 1,779 nasopharyngeal swabs were collected from 136 children for whom vaccination data were available. The prevalence of bacterial carriage was high: 82.2% S. pneumoniae, 30.6%, S.aureus, 27.8% H. influenzae. Carriage of H. influenzae (OR = 0.36; 95% CI: 0.13, 0.99) and S. pneumoniae (OR = 0.25; 95% CI: 0.07, 0.90) were significantly reduced after measles-yellow fever vaccination; while DTP-Hib-HepB had no effect on bacterial carriage.
  
  
  CONCLUSIONS
  Nasopharyngeal bacterial carriage is unaffected by DTP-Hib-HepB vaccination and reduced after measles-yellow fever vaccination.
authors: MRC Tropical Epidemiology Group, Faculty of Epidemiology and Population Health, London School of Hygiene & Tropical Medicine, London, UK.
authors: Christian
authors: C
authors: Bottomley
authors: Medical Research Council Unit, Banjul, The Gambia.
authors: Abdoulie
authors: A
authors: Bojang
authors: MRC Tropical Epidemiology Group, Faculty of Epidemiology and Population Health, London School of Hygiene & Tropical Medicine, London, UK.
authors: Peter G
authors: PG
authors: Smith
authors: Medical Research Council Unit, Banjul, The Gambia.
authors: Ousainou
authors: O
authors: Darboe
authors: Medical Research Council Unit, Banjul, The Gambia.
authors: Martin
authors: M
authors: Antonio
authors: Medical Research Council Unit, Banjul, The Gambia.
authors: Ebenezer
authors: E
authors: Foster-Nyarko
authors: Medical Research Council Unit, Banjul, The Gambia.
authors: Beate
authors: B
authors: Kampmann
authors: Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, UK.
authors: Brian
authors: B
authors: Greenwood
authors: Medical Research Council Unit, Banjul, The Gambia.
authors: Umberto
authors: U
authors: D'Alessandro
authors: Medical Research Council Unit, Banjul, The Gambia.
authors: Anna
authors: A
authors: Roca
keywords: DTP; Measles; Nasopharyngeal bacterial carriage; Non-specific vaccine effects
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