title: Human Papillomavirus Vaccination of Boys and Extended Catch-up Vaccination: Effects on the Resilience of Programs.
abstract: BACKGROUND
  Decreasing human papillomavirus (HPV) vaccine prices makes scaling up of vaccination programs attractive for countries that initially targeted 1 or a few birth cohorts of girls and/or achieved low coverage. This article aims to compare the impact of alternative HPV vaccination strategies, using data from Sweden, a high-income country that has experienced vaccine price changes.
  
  
  METHODS
  Using an HPV transmission model, we compared the existing vaccination program to alternatives, accounting for a 1-time catch-up vaccination of 22-26-year-old women, with or without routine vaccination of school-age boys, and for a 1-time catch-up vaccination of males aged 13-26 years. We also assessed the resilience of vaccination alternatives to coverage reduction.
  
  
  RESULTS
  On the basis of an HPV16/18 prevalence of 12% before the HPV vaccine era, extended catch-up vaccination for females and males yielded relative reductions in the HPV prevalence of 49.4% and 55.6%, respectively, during the first 10 years after the start of each vaccination strategy, whereas the existing program yielded a relative reduction of 38.6% during the same period. The increased prevalence reduction due to catch-up vaccination continued for about 30 years. As compared to female-only routine and extended catch-up vaccination, routine vaccination of males with or without catch-up was, respectively, 12.6-fold and 7.2-fold more resilient to coverage reduction.
  
  
  CONCLUSIONS
  Vaccination strategies based on catch-up vaccination of females and males are effective for accelerating HPV prevalence reduction. Inclusion of routine male vaccination improves the resilience of vaccination programs.
authors.affiliation: Department of Medical Epidemiology and Biostatistics.
authors.forename: K Miriam
authors.initials: KM
authors.lastname: Elfström
authors.affiliation: Department of Translational Medicine, University of Piemonte Orientale Avogadro, Novara Unit of Cancer Epidemiology, Department of Medical Sciences, University of Turin, Italy International Agency for Research on Cancer, Lyon, France.
authors.forename: Fulvio
authors.initials: F
authors.lastname: Lazzarato
authors.affiliation: International Agency for Research on Cancer, Lyon, France.
authors.forename: Silvia
authors.initials: S
authors.lastname: Franceschi
authors.affiliation: Department of Medical Epidemiology and Biostatistics Department of Laboratory Medicine, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Joakim
authors.initials: J
authors.lastname: Dillner
authors.affiliation: International Agency for Research on Cancer, Lyon, France.
authors.forename: Iacopo
authors.initials: I
authors.lastname: Baussano
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D005260:Female; D006801:Humans; D017589:Immunization Programs / Q000191:economics / Q000458:organization & administration*; D007115:Immunization Schedule; D008297:Male; D027383:Papillomaviridae / Q000145:classification* / Q000276:immunology; D030361:Papillomavirus Infections / Q000517:prevention & control*; D053918:Papillomavirus Vaccines / Q000008:administration & dosage* / Q000191:economics / Q000276:immunology; D014611:Vaccination; D055815:Young Adult
chemical_list: D053918:Papillomavirus Vaccines
keywords: catch-up; coverage reduction; gender neutral; human papillomavirus vaccination; resilience