title: Association of varying number of doses of quadrivalent human papillomavirus vaccine with incidence of condyloma.
abstract: OBJECTIVE
  Determining vaccine dose-level protection is essential to minimize program costs and increase mass vaccination program feasibility. Currently, a 3-dose vaccination schedule is recommended for both the quadrivalent and bivalent human papillomavirus (HPV) vaccines. Although the primary goal of HPV vaccination programs is to prevent cervical cancer, condyloma related to HPV types 6 and 11 is also prevented with the quadrivalent vaccine and represents the earliest measurable preventable disease outcome for the HPV vaccine.
  
  
  OBJECTIVE
  To examine the association between quadrivalent HPV vaccination and first occurrence of condyloma in relation to vaccine dose in a population-based setting.
  
  
  METHODS
  An open cohort of all females aged 10 to 24 years living in Sweden (n = 1,045,165) was followed up between 2006 and 2010 for HPV vaccination and first occurrence of condyloma using the Swedish nationwide population-based health data registers.
  
  
  METHODS
  Incidence rate ratios (IRRs) and incidence rate differences (IRDs) of condyloma were estimated using Poisson regression with vaccine dose as a time-dependent exposure, adjusting for attained age and parental education, and stratified on age at first vaccination. To account for prevalent infections, models included a buffer period of delayed case counting.
  
  
  RESULTS
  A total of 20,383 incident cases of condyloma were identified during follow-up, including 322 cases after receipt of at least 1 dose of the vaccine. For individuals aged 10 to 16 years at first vaccination, receipt of 3 doses was associated with an IRR of 0.18 (95% CI, 0.15-0.22) for condyloma, whereas receipt of 2 doses was associated with an IRR of 0.29 (95% CI, 0.21-0.40). One dose was associated with an IRR of 0.31 (95% CI, 0.20-0.49), which corresponds to an IRD of 384 cases (95% CI, 305-464) per 100,000 person-years, compared with no vaccination. The corresponding IRDs for 2 doses were 400 cases (95% CI, 346-454) and for 3 doses, 459 cases (95% CI, 437-482). The number of prevented cases between 3 and 2 doses was 59 (95% CI, 2-117) per 100,000 person-years.
  
  
  CONCLUSIONS
  Although maximum reduction in condyloma risk was seen after receipt of 3 doses of quadrivalent HPV vaccine, receipt of 2 vaccine doses was also associated with a considerable reduction in condyloma risk. The implications of these findings for the relationship between number of vaccine doses and cervical cancer risk require further investigation.
authors: Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden.
authors: Eva
authors: E
authors: Herweijer
authors: Department of Communicable Disease Control and Prevention for Stockholm County, Stockholm, Sweden3Department of Medicine, Infectious Disease Unit, Karolinska Institutet, Stockholm, Sweden.
authors: Amy
authors: A
authors: Leval
authors: Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden.
authors: Alexander
authors: A
authors: Ploner
authors: Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden.
authors: Sandra
authors: S
authors: Eloranta
authors: Department of Medicine, Clinical Epidemiology Unit, Karolinska Institutet, Stockholm, Sweden.
authors: Julia Fridman
authors: JF
authors: Simard
authors: Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden.
authors: Joakim
authors: J
authors: Dillner
authors: Swedish Institute for Communicable Disease Control, Stockholm, Sweden6Faculty of Medicine, Department of Clinical Sciences in Malmö, Lund University, Malmö, Sweden7Department of Occupational and Environmental Dermatology, Skåne University Hospital, Malmö.
authors: Eva
authors: E
authors: Netterlid
authors: Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden.
authors: Pär
authors: P
authors: Sparén
authors: Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden.
authors: Lisen
authors: L
authors: Arnheim-Dahlström
mesh_terms: D000293:Adolescent; D002648:Child; D015331:Cohort Studies; D003218:Condylomata Acuminata / Q000453:epidemiology* / Q000517:prevention & control*; D003362:Cost-Benefit Analysis; D005260:Female; D052140:Human papillomavirus 11; D052163:Human papillomavirus 6; D006801:Humans; D015994:Incidence; D030361:Papillomavirus Infections / Q000517:prevention & control*; D053918:Papillomavirus Vaccines / Q000008:administration & dosage*; D012042:Registries / Q000706:statistics & numerical data; D013548:Sweden / Q000453:epidemiology; D002583:Uterine Cervical Neoplasms / Q000517:prevention & control; D014611:Vaccination / Q000706:statistics & numerical data*; D055815:Young Adult
chemical_list: D053918:Papillomavirus Vaccines