title: Changes in serogroup and genotype prevalence among carried meningococci in the United Kingdom during vaccine implementation.
abstract: BACKGROUND
  Herd immunity is important in the effectiveness of conjugate polysaccharide vaccines against encapsulated bacteria. A large multicenter study investigated the effect of meningococcal serogroup C conjugate vaccine introduction on the meningococcal population.
  
  
  METHODS
  Carried meningococci in individuals aged 15-19 years attending education establishments were investigated before and for 2 years after vaccine introduction. Isolates were characterized by multilocus sequence typing, serogroup, and capsular region genotype and changes in phenotypes and genotypes assessed.
  
  
  RESULTS
  A total of 8462 meningococci were isolated from 47 765 participants (17.7%). Serogroup prevalence was similar over the 3 years, except for decreases of 80% for serogroup C and 40% for serogroup 29E. Clonal complexes were associated with particular serogroups and their relative proportions fluctuated, with 12 statistically significant changes (6 up, 6 down). The reduction of ST-11 complex serogroup C meningococci was probably due to vaccine introduction. Reasons for a decrease in serogroup 29E ST-254 meningococci (from 1.8% to 0.7%) and an increase in serogroup B ST-213 complex meningococci (from 6.7% to 10.6%) were less clear.
  
  
  CONCLUSIONS
  Natural fluctuations in carried meningococcal genotypes and phenotypes a can be affected by the use of conjugate vaccines, and not all of these changes are anticipatable in advance of vaccine introduction.
authors: Department of Zoology, University of Oxford, United Kingdom.
authors: Ana Belén
authors: AB
authors: Ibarz-Pavón
authors: Jenny
authors: J
authors: Maclennan
authors: Nicholas J
authors: NJ
authors: Andrews
authors: Stephen J
authors: SJ
authors: Gray
authors: Rachel
authors: R
authors: Urwin
authors: Stuart C
authors: SC
authors: Clarke
authors: A Mark
authors: AM
authors: Walker
authors: Meirion R
authors: MR
authors: Evans
authors: J Simon
authors: JS
authors: Kroll
authors: Keith R
authors: KR
authors: Neal
authors: Dlawer
authors: D
authors: Ala'aldeen
authors: Derrick W
authors: DW
authors: Crook
authors: Kathryn
authors: K
authors: Cann
authors: Sarah
authors: S
authors: Harrison
authors: Richard
authors: R
authors: Cunningham
authors: David
authors: D
authors: Baxter
authors: Edward
authors: E
authors: Kaczmarski
authors: Noel D
authors: ND
authors: McCarthy
authors: Keith A
authors: KA
authors: Jolley
authors: J Claire
authors: JC
authors: Cameron
authors: James M
authors: JM
authors: Stuart
authors: Martin C J
authors: MC
authors: Maiden
mesh_terms: D000293:Adolescent; D000328:Adult; D016667:Bacterial Capsules / Q000235:genetics / Q000378:metabolism; D002353:Carrier State / Q000276:immunology; D005838:Genotype; D006801:Humans; D032521:Immunity, Herd / Q000276:immunology*; D032541:Mass Vaccination; D008585:Meningitis, Meningococcal / Q000235:genetics / Q000276:immunology / Q000517:prevention & control*; D022401:Meningococcal Vaccines / Q000008:administration & dosage*; D058885:Multilocus Sequence Typing; D019158:N-Acetylneuraminic Acid / Q000235:genetics* / Q000378:metabolism; D009345:Neisseria meningitidis / Q000235:genetics* / Q000276:immunology*; D012703:Serotyping; D006113:United Kingdom; D055815:Young Adult
chemical_list: D022401:Meningococcal Vaccines; C410218:serogroup C meningococcal conjugate vaccine; D019158:N-Acetylneuraminic Acid