title: Continuing reductions in HPV 16/18 in a population with high coverage of bivalent HPV vaccination in England: an ongoing cross-sectional study.
abstract: OBJECTIVE
  The human papillomavirus (HPV) immunisation programme in England was introduced in 2008. Monitoring changes in type-specific HPV prevalence allows assessment of the population impact of this vaccination programme.
  
  
  METHODS
  Residual vulva-vaginal swab specimens were collected from young sexually active women (aged 16-24 years) attending for chlamydia screening across England. Specimens were collected between 2010 and 2013 for type-specific HPV-DNA testing. HPV prevalence was compared to a similar survey conducted in 2008 prior to the introduction of HPV vaccination.
  
  
  RESULTS
  A total of 7321 specimens collected in the postvaccination period, and 2354 specimens from the prevaccination period were included in this analysis. Among the individuals aged 16-18 years, with an estimated vaccination coverage of 67%, the prevalence of HPV16/18 infection decreased from 17.6% in 2008 to 6.1% in the postvaccination period. Within the postvaccination period, there was a trend towards lower HPV16/18 prevalence with higher vaccination coverage and increasing time since vaccine introduction from 8.5% in the period 2-3 years postvaccination to 4.0% in the period 4-5 years postvaccination. The prevalence of HPV31 reduced from 3.7% in the prevaccination period to 0.9% after vaccine introduction, although this no longer reached statistical significance after additional consideration of the uncertainty due to the assay change. Smaller reductions were seen in the individuals aged 19-21 years with lower estimated vaccination coverage, but there was no evidence of a reduction in the older unvaccinated women. Some overall increase in non-vaccine types was seen in the youngest age groups (ORs (95% CI); 1.3 (1.0 to 1.7) and 1.5 (1.1 to 2.0) for individuals aged 16-18 and 19-21 years, respectively, when adjusted for known population changes and the change in assay) although this should be interpreted with caution given the potential unmasking effect.
  
  
  CONCLUSIONS
  These data demonstrate a reduction in the HPV vaccine types in the age group with the highest HPV vaccination coverage.
authors: HIV & STI Department, Centre for Infectious Disease Surveillance and Control, Public Health England, London, UK.
authors: David
authors: D
authors: Mesher
authors: Virus Reference Department, Public Health England, London, UK.
authors: Kavita
authors: K
authors: Panwar
authors: Department of Epidemiology & Population Health, London School of Hygiene and Tropical Medicine, London, UK.
authors: Sara L
authors: SL
authors: Thomas
authors: Virus Reference Department, Public Health England, London, UK.
authors: Simon
authors: S
authors: Beddows
authors: HIV & STI Department, Centre for Infectious Disease Surveillance and Control, Public Health England, London, UK.
authors: Kate
authors: K
authors: Soldan
mesh_terms: D000293:Adolescent; D003430:Cross-Sectional Studies; D004739:England / Q000453:epidemiology; D005260:Female; D052162:Human papillomavirus 16; D052161:Human papillomavirus 18; D006801:Humans; D030361:Papillomavirus Infections / Q000453:epidemiology / Q000517:prevention & control* / Q000821:virology; D053918:Papillomavirus Vaccines; D011159:Population Surveillance; D015995:Prevalence; D002583:Uterine Cervical Neoplasms / Q000453:epidemiology / Q000517:prevention & control* / Q000821:virology; D014611:Vaccination; D055815:Young Adult
chemical_list: D053918:Papillomavirus Vaccines
keywords: EPIDEMIOLOGY