title: Early impact of Ontario's human papillomavirus (HPV) vaccination program on anogenital warts (AGWs): A population-based assessment.
abstract: This study aimed to evaluate the early population impact of Ontario's school-based human papillomavirus (HPV) vaccination program, implemented in September 2007 for grade 8 females, by comparing anogenital wart (AGW) health care utilization before and after vaccine program implementation, in program-eligible and program-ineligible cohorts, focusing on 15-26year olds.
  
  
  
  Using a retrospective longitudinal population-based study design, health administrative data were used to identify incident AGWs and total health service utilization (HSU) for AGWs for Ontario residents 15years and older between April 1 2004 and March 31 2014. The study period was divided into two eras: the pre-vaccine program era and the vaccine program era. Negative binomial models were generated to analyze trends across time by age group and sex. We adjusted female rates for routine Papanicolaou (Pap) testing to address spillover effects of Pap smear policy changes on AGW diagnosis.
  
  
  
  Between fiscal years 2004 and 2013, AGW incidence decreased 2.6% on average per year in 15-17year old females, and total HSU for AGWs decreased an average of 4.8% and 2.2% per year in 15-17 and 18-20year old females. Comparing the vaccine era to the pre-vaccine era, AGW incidence decreased 6.5% in 18-20year old females, and AGW HSU decreased 13.8%, 11.1%, and 10.0% in 15-17, 18-20, and 21-23year old females respectively. In contrast, male AGW incidence rates increased an average of 4.1%, 2.8%, and 0.9% per year in 15-17, 21-23, and 24-26year old males respectively. AGW incidence rates increased 12.2% in 15-17year old males from the pre-vaccine to vaccine era.
  
  
  
  The decline in AGW incidence and HSU in program-eligible females suggests the school-based HPV vaccination program has had an early population impact in Ontario. The increasing AGW incidence in males suggests no early evidence of herd effects in males.
authors.affiliation: Public Health Ontario, 480 University Avenue, Suite 300, Toronto, ON M5G 1V2, Canada. Electronic address: fiona.guerra@gmail.com.
authors.forename: Fiona M
authors.initials: FM
authors.lastname: Guerra
authors.affiliation: Public Health Ontario, 480 University Avenue, Suite 300, Toronto, ON M5G 1V2, Canada; Dalla Lana School of Public Health, University of Toronto, 155 College St, Toronto, ON M5T 3M7, Canada; Institute for Clinical Evaluative Sciences, Veterans Hill Trail, 2075 Bayview Avenue G106, Toronto, ON M4N 3M5, Canada. Electronic address: laura.rosella@utoronto.ca.
authors.forename: Laura C
authors.initials: LC
authors.lastname: Rosella
authors.affiliation: Department of Family and Community Medicine, University of Toronto, 500 University Ave, Toronto, ON M5G 1V7, Canada; Women's College Hospital and Women's College Research Institute, 790 Bay St, Toronto, ON M5G 1N8, Canada. Electronic address: sheila.dunn@wchospital.ca.
authors.forename: Sheila
authors.initials: S
authors.lastname: Dunn
authors.affiliation: Public Health Ontario, 480 University Avenue, Suite 300, Toronto, ON M5G 1V2, Canada; Dalla Lana School of Public Health, University of Toronto, 155 College St, Toronto, ON M5T 3M7, Canada; Institute for Clinical Evaluative Sciences, Veterans Hill Trail, 2075 Bayview Avenue G106, Toronto, ON M4N 3M5, Canada. Electronic address: sarah.wilson@oahpp.ca.
authors.forename: Sarah E
authors.initials: SE
authors.lastname: Wilson
authors.affiliation: Public Health Ontario, 480 University Avenue, Suite 300, Toronto, ON M5G 1V2, Canada. Electronic address: Cynthia.Chen@oahpp.ca.
authors.forename: Cynthia
authors.initials: C
authors.lastname: Chen
authors.affiliation: Public Health Ontario, 480 University Avenue, Suite 300, Toronto, ON M5G 1V2, Canada; Dalla Lana School of Public Health, University of Toronto, 155 College St, Toronto, ON M5T 3M7, Canada. Electronic address: shelley.deeks@oahpp.ca.
authors.forename: Shelley L
authors.initials: SL
authors.lastname: Deeks
mesh_terms: D000293:Adolescent; D000328:Adult; D003218:Condylomata Acuminata / Q000517:prevention & control*; D005260:Female; D006801:Humans; D017589:Immunization Programs; D015994:Incidence; D008137:Longitudinal Studies; D008297:Male; D009864:Ontario; D065006:Papanicolaou Test; D030361:Papillomavirus Infections / Q000517:prevention & control*; D053918:Papillomavirus Vaccines / Q000627:therapeutic use*; D012189:Retrospective Studies; D055815:Young Adult
chemical_list: D053918:Papillomavirus Vaccines
keywords: Epidemiology; Genital warts; HPV; Health services research; Human papillomavirus; STI; Vaccine