title: Immune Responses After 2 Versus 3 Doses of HPV Vaccination up to 4½ Years After Vaccination: An Observational Study Among Dutch Routinely Vaccinated Girls.
abstract: BACKGROUND
  In 2014 the Netherlands switched from 3 to 2 doses for routine vaccination with the prophylactic bivalent human papillomavirus (HPV) vaccine. The current study explored whether antibody responses are noninferior after 2 versus 3 doses in girls.
  
  
  METHODS
  Girls vaccinated at 12 years of age with 2 (at 0 and 6 months) or 3 doses (at 0, 1, and 6 months) of the bivalent HPV vaccine were identified in the vaccination registration system. Type-specific antibody concentrations and avidity against HPV-16/18/31/33/45/52/58 were assessed. Analyses were stratified for time since the first dose (0-2, 2-3, 3-4, or 4-4½ years). Noninferiority (margin, 0.5) of the 2- versus the 3-dose schedule in girls was examined.
  
  
  RESULTS
  Geometric mean concentrations (GMCs) for vaccine types were only noninferior for 2 versus 3 doses for HPV-18 (at 2-3 years after the first dose; GMC ratio, 0.89; 95% confidence interval, .57-1.38) For vaccine types and cross-protective types (HPV-16/18/31/33/45), the avidity index was noninferior for the 2-dose compared with the 3-dose schedule, except for HPV-31 at 4-4½ years after the first dose and HPV-33 at 3-4 and 4-4½ years.
  
  
  CONCLUSIONS
  GMCs for HPV-16/18 were not noninferior for 2 versus 3 doses, except for HPV-18 (at 2-3 years after first dose). However, antibody avidity for these types showed noninferiority, independent of concentrations.
authors.affiliation: Center for Infectious Disease Control, National Institute for Public Health and the Environment, Bilthoven, the Netherlands, and.|Department of Pathology, VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: Robine
authors.initials: R
authors.lastname: Donken
authors.affiliation: Center for Infectious Disease Control, National Institute for Public Health and the Environment, Bilthoven, the Netherlands, and.
authors.forename: Tessa M
authors.initials: TM
authors.lastname: Schurink-Van't Klooster
authors.affiliation: Center for Infectious Disease Control, National Institute for Public Health and the Environment, Bilthoven, the Netherlands, and.
authors.forename: Rutger M
authors.initials: RM
authors.lastname: Schepp
authors.affiliation: Center for Infectious Disease Control, National Institute for Public Health and the Environment, Bilthoven, the Netherlands, and.
authors.forename: Fiona R M
authors.initials: FR
authors.lastname: van der Klis
authors.affiliation: Center for Infectious Disease Control, National Institute for Public Health and the Environment, Bilthoven, the Netherlands, and.
authors.forename: Mirjam J
authors.initials: MJ
authors.lastname: Knol
authors.affiliation: Department of Pathology, VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: Chris J L M
authors.initials: CJ
authors.lastname: Meijer
authors.affiliation: Center for Infectious Disease Control, National Institute for Public Health and the Environment, Bilthoven, the Netherlands, and.
authors.forename: Hester E
authors.initials: HE
authors.lastname: de Melker
mesh_terms: D000293:Adolescent; D000914:Antibodies, Viral / Q000097:blood / Q000276:immunology; D000915:Antibody Affinity; D002648:Child; D004306:Dose-Response Relationship, Immunologic; D005260:Female; D006801:Humans; D000071497:Immunogenicity, Vaccine; D030361:Papillomavirus Infections / Q000276:immunology / Q000517:prevention & control; D053918:Papillomavirus Vaccines / Q000008:administration & dosage / Q000276:immunology*; D016037:Single-Blind Method
chemical_list: D000914:Antibodies, Viral; D053918:Papillomavirus Vaccines
keywords: GMC; HPV; antibody concentration; avidity; three-dose schedule.; two-dose schedule; vaccine