title: Long-term impact of human papillomavirus vaccination on infection rates, cervical abnormalities, and cancer incidence.
abstract: BACKGROUND
  Vaccination against human papillomavirus (HPV) types 16/18 is being implemented in many countries. There may be indirect benefit of HPV vaccination to nonvaccinated women, who may experience a reduced risk of infection with vaccine-preventable types (herd immunity). We attempt to disentangle the direct and indirect effects of HPV vaccination, while accounting for 14 oncogenic HPV types in a dynamic modeling framework.
  
  
  METHODS
  On the basis of vaccine uptake among preadolescent girls in the Netherlands, we calculated how heterosexual transmission of HPV-16/18 is expected to change as a result of vaccination, and used these predictions in an individual-based simulation model of cervical carcinogenesis that considers 14 high-risk HPV types. Models were parameterized to match prevaccine data on type-specific HPV infection and cervical disease.
  
  
  RESULTS
  At 50% vaccine coverage, the estimated lifetime infection risk in nonvaccinated women dropped from 0.46 (95% credible interval = 0.35-0.54) to 0.37 (0.26-0.46) for HPV-16, and from 0.40 (0.32-0.46) to 0.31 (0.22-0.36) [corrected] for HPV-18. For the whole population, we calculated an eventual 47% reduction in cervical cancer incidence, with 1 in 4 cases prevented among nonvaccinated women. The number of indirectly averted cancer cases was highest with vaccine coverage between 50% and 70%, approximating 70 cases per 100,000 women born from 2010 onward.
  
  
  CONCLUSIONS
  HPV-16/18 vaccination of preadolescent girls will markedly lower infection rates among nonvaccinated women. Reduced transmission of vaccine-preventable HPV becomes a prominent aspect of cervical cancer control, especially in populations with moderate vaccine coverage.
authors.affiliation: Department of Epidemiology and Biostatistics, VU University Medical Centre, Amsterdam, The Netherlands. j.bogaards@vumc.nl
authors.forename: Johannes A
authors.initials: JA
authors.lastname: Bogaards
authors.forename: Veerle M H
authors.initials: VM
authors.lastname: Coupé
authors.forename: Maria
authors.initials: M
authors.lastname: Xiridou
authors.forename: Chris J L M
authors.initials: CJ
authors.lastname: Meijer
authors.forename: Jacco
authors.initials: J
authors.lastname: Wallinga
authors.forename: Johannes
authors.initials: J
authors.lastname: Berkhof
mesh_terms: D000293:Adolescent; D002648:Child; D005260:Female; D052162:Human papillomavirus 16; D052161:Human papillomavirus 18; D006801:Humans; D032521:Immunity, Herd; D008954:Models, Biological; D009426:Netherlands / Q000453:epidemiology; D030361:Papillomavirus Infections / Q000453:epidemiology / Q000276:immunology / Q000517:prevention & control* / Q000635:transmission; D053918:Papillomavirus Vaccines; D013997:Time Factors; D002583:Uterine Cervical Neoplasms / Q000453:epidemiology / Q000276:immunology / Q000517:prevention & control*; D014611:Vaccination / Q000706:statistics & numerical data*
chemical_list: D053918:Papillomavirus Vaccines