title: Immunogenicity of quadrivalent HPV vaccine among girls 11 to 13 Years of age vaccinated using alternative dosing schedules: results 29 to 32 months after third dose.
abstract: BACKGROUND
  Immune response to quadrivalent human papillomavirus (HPV) vaccine delivered at 0, 2, and 6 months in young adolescent females plateaus around 24 months after immunization. Antibody levels >24 months postvaccination using extended dosing schedules is unknown.
  
  
  METHODS
  We conducted a follow-up immunogenicity study of adolescent girls in Vietnam who participated in a noninferiority trial to investigate whether immune responses using 3 alternative dosing schedules (0, 3, 9 months; 0, 6, 12 months; or 0, 12, 24 months) are noninferior to the standard schedule at >2 years after immunization.
  
  
  RESULTS
  Quadrivalent HPV vaccine immunogenicity delivered on 3 alternative dosing schedules was noninferior for types 6, 11, 16, and 18 at 32 months post-dose 3 compared to the standard schedule. Pre-dose 3 antibody levels for the 0, 12, 24 month schedule were similar to those measured 32-months post-dose 3.
  
  
  CONCLUSIONS
  We found similar antibody concentrations ≥29 months after 3 doses of HPV vaccine regardless of dose-timing, and extended schedules do not produce inferior immune responses. Our findings also suggested that 2 doses of HPV vaccine delivered at 0 and 12 months might afford similar protection. Evidence supporting dosing flexibility could be important for national HPV vaccination policies.
authors.affiliation: PATH, Seattle, Washington.
authors.forename: D Scott
authors.initials: DS
authors.lastname: Lamontagne
authors.forename: Vu Dinh
authors.initials: VD
authors.lastname: Thiem
authors.forename: Vu Minh
authors.initials: VM
authors.lastname: Huong
authors.forename: Yuxiao
authors.initials: Y
authors.lastname: Tang
authors.forename: Kathleen M
authors.initials: KM
authors.lastname: Neuzil
mesh_terms: D000293:Adolescent; D052685:Alphapapillomavirus / Q000276:immunology*; D000914:Antibodies, Viral / Q000097:blood; D002648:Child; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007115:Immunization Schedule; D030361:Papillomavirus Infections / Q000097:blood / Q000453:epidemiology / Q000276:immunology / Q000517:prevention & control*; D053918:Papillomavirus Vaccines / Q000008:administration & dosage* / Q000097:blood / Q000276:immunology*; D016032:Randomized Controlled Trials as Topic; D014744:Vietnam / Q000453:epidemiology
chemical_list: D000914:Antibodies, Viral; D053918:Papillomavirus Vaccines
keywords: HPV vaccine; Vietnam; adolescents; human papillomavirus; immunogenicity; vaccination schedule