title: Potential benefits of second-generation human papillomavirus vaccines.
abstract: BACKGROUND
  Current prophylactic vaccines against human papillomavirus (HPV) target two oncogenic types (16 and 18) that contribute to 70% of cervical cancer cases worldwide. Our objective was to quantify the range of additional benefits conferred by second-generation HPV prophylactic vaccines that are expected to expand protection to five additional oncogenic types (31, 33, 45, 52 and 58).
  
  
  METHODS
  A microsimulation model of HPV and cervical cancer calibrated to epidemiological data from two countries (Kenya and Uganda) was used to estimate reductions in lifetime risk of cervical cancer from the second-generation HPV vaccines. We explored the independent and joint impact of uncertain factors (i.e., distribution of HPV types, co-infection with multiple HPV types, and unidentifiable HPV types in cancer) and vaccine properties (i.e., cross-protection against non-targeted HPV types), compared against currently-available vaccines.
  
  
  RESULTS
  Assuming complete uptake of the second-generation vaccine, reductions in lifetime cancer risk were 86.3% in Kenya and 91.8% in Uganda, representing an absolute increase in cervical cancer reduction of 26.1% in Kenya and 17.9% in Uganda, compared with complete uptake of current vaccines. The range of added benefits was 19.6% to 29.1% in Kenya and 14.0% to 19.5% in Uganda, depending on assumptions of cancers attributable to multiple HPV infections and unidentifiable HPV types. These effects were blunted in both countries when assuming vaccine cross-protection with both the current and second-generation vaccines.
  
  
  CONCLUSIONS
  Second-generation HPV vaccines that protect against additional oncogenic HPV types have the potential to improve cervical cancer prevention. Co-infection with multiple HPV infections and unidentifiable HPV types can influence vaccine effectiveness, but the magnitude of effect may be moderated by vaccine cross-protective effects. These benefits must be weighed against the cost of the vaccines in future analyses.
authors.affiliation: Harvard Interfaculty Initiative in Health Policy, Cambridge, MA, USA. kiatpong@fas.harvard.edu
authors.forename: Sorapop
authors.initials: S
authors.lastname: Kiatpongsan
authors.forename: Nicole Gastineau
authors.initials: NG
authors.lastname: Campos
authors.forename: Jane J
authors.initials: JJ
authors.lastname: Kim
mesh_terms: D060085:Coinfection / Q000276:immunology / Q000517:prevention & control / Q000821:virology; D056738:Cross Protection / Q000276:immunology; D005260:Female; D052162:Human papillomavirus 16 / Q000276:immunology; D052161:Human papillomavirus 18 / Q000276:immunology; D006801:Humans; D007630:Kenya; D053918:Papillomavirus Vaccines / Q000276:immunology*; D014454:Uganda; D002583:Uterine Cervical Neoplasms / Q000276:immunology / Q000517:prevention & control / Q000821:virology
chemical_list: D053918:Papillomavirus Vaccines