title: Introduction and sustained high coverage of the HPV bivalent vaccine leads to a reduction in prevalence of HPV 16/18 and closely related HPV types.
abstract: BACKGROUND
  In 2008, a national human papillomavirus (HPV) immunisation programme began in Scotland for 12-13 year old females with a three-year catch-up campaign for those under the age of 18. Since 2008, three-dose uptake of bivalent vaccine in the routine cohort aged 12-13 has exceeded 90% annually, while in the catch-up cohort overall uptake is 66%.
  
  
  METHODS
  To monitor the impact of HPV immunisation, a programme of national surveillance was established (pre and post introduction) which included yearly sampling and HPV genotyping of women attending for cervical screening at age 20. By linking individual vaccination, screening and HPV testing records, we aim to determine the impact of the immunisation programme on circulating type-specific HPV infection particularly for four outcomes: (i) the vaccine types HPV 16 or 18 (ii) types considered to be associated with cross-protection: HPV 31, 33 or 45; (iii) all other high-risk types and (iv) any HPV.
  
  
  RESULTS
  From a total of 4679 samples tested, we demonstrate that three doses (n=1100) of bivalent vaccine are associated with a significant reduction in prevalence of HPV 16 and 18 from 29.8% (95% confidence interval 28.3, 31.3%) to 13.6% (95% confidence interval 11.7, 15.8%). The data also suggest cross-protection against HPV 31, 33 and 45. HPV 51 and 56 emerged as the most prevalent (10.5% and 9.6%, respectively) non-vaccine high-risk types in those vaccinated, but at lower rates than HPV 16 (25.9%) in those unvaccinated.
  
  
  CONCLUSIONS
  This data demonstrate the positive impact of bivalent vaccination on the prevalence of HPV 16, 18, 31, 33 and 45 in the target population and is encouraging for countries which have achieved high-vaccine uptake.
authors.affiliation: Department of Mathematics and Statistics, University of Strathclyde, Glasgow, Scotland.
authors.forename: K
authors.initials: K
authors.lastname: Kavanagh
authors.affiliation: Health Protection Scotland, Glasgow, Scotland.
authors.forename: K G J
authors.initials: KG
authors.lastname: Pollock
authors.affiliation: Health Protection Scotland, Glasgow, Scotland.
authors.forename: A
authors.initials: A
authors.lastname: Potts
authors.affiliation: Health Protection Scotland, Glasgow, Scotland.
authors.forename: J
authors.initials: J
authors.lastname: Love
authors.affiliation: Scottish Human Papillomavirus Reference Laboratory, Edinburgh, Scotland.
authors.forename: K
authors.initials: K
authors.lastname: Cuschieri
authors.affiliation: Scottish Human Papillomavirus Reference Laboratory, Edinburgh, Scotland.
authors.forename: H
authors.initials: H
authors.lastname: Cubie
authors.affiliation: 1] Department of Mathematics and Statistics, University of Strathclyde, Glasgow, Scotland [2] Health Protection Scotland, Glasgow, Scotland [3] International Prevention Research Institute, Lyon, France.
authors.forename: C
authors.initials: C
authors.lastname: Robertson
authors.affiliation: Health Protection Scotland, Glasgow, Scotland.
authors.forename: M
authors.initials: M
authors.lastname: Donaghy
mesh_terms: D003430:Cross-Sectional Studies; D004306:Dose-Response Relationship, Immunologic; D005260:Female; D005838:Genotype; D052162:Human papillomavirus 16 / Q000235:genetics / Q000276:immunology*; D052161:Human papillomavirus 18 / Q000235:genetics / Q000276:immunology*; D006801:Humans; D030361:Papillomavirus Infections / Q000453:epidemiology / Q000517:prevention & control*; D053918:Papillomavirus Vaccines / Q000008:administration & dosage*; D015995:Prevalence; D012680:Sensitivity and Specificity; D002583:Uterine Cervical Neoplasms / Q000453:epidemiology / Q000517:prevention & control* / Q000821:virology; D014611:Vaccination; D064166:Vaccine Potency; D055815:Young Adult
chemical_list: D053918:Papillomavirus Vaccines
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