title: Long-term study of a quadrivalent human papillomavirus vaccine.
abstract: BACKGROUND
  We present a long-term safety, immunogenicity, and effectiveness study of a quadrivalent human papillomavirus (HPV4) vaccine.
  
  
  METHODS
  Sexually naive boys and girls aged 9 to 15 years (N = 1781) were assigned (2:1) to receive HPV4 vaccine or saline placebo at day 1 and months 2 and 6. At month 30, the placebo group (n = 482) received HPV4 vaccine following the same regimen and both cohorts were followed through month 96. Subjects ≥ 16 years were eligible for effectiveness evaluations. The primary objective was to evaluate the long-term anti-HPV6/11/16/18 serological levels. The secondary objective was to estimate vaccine effectiveness against HPV6/11/16/18-related persistent infection or disease.
  
  
  RESULTS
  For each of the HPV4 vaccine types, vaccination-induced anti-HPV response persisted through month 96. Among 429 subjects who received HPV4 vaccine at a mean age of 12, none developed HPV6/11/16/18-related disease or persistent infection of ≥ 12 months' duration. Acquisition of new sexual partners (among those ≥ 16 years) was ∼1 per year. Subjects receiving HPV4 vaccine at month 30 (mean age 15 years) had a similar baseline rate of seropositivity to ≥ 1 of the 4 HPV types to those vaccinated at day 1 (mean age 12 years; 1.9% [9 of 474] vs 1.7% [20 of 1157]); however, 4 of the 9 subjects vaccinated at the later age were seropositive to 3 vaccine types, indicating previous HPV exposure. No new significant serious adverse events were observed for 8 years postvaccination in both genders.
  
  
  CONCLUSIONS
  When administered to adolescents, the HPV4 vaccine demonstrated durability in clinically effective protection and sustained antibody titers over 8 years.
authors.affiliation: Department of Obstetrics and Gynecology, Georgia Regents University, Augusta, Georgia; dferris@gru.edu.
authors.forename: Daron
authors.initials: D
authors.lastname: Ferris
authors.affiliation: Department of Pediatrics, Phramongkutklao Hospital, Bangkok, Thailand;
authors.forename: Rudiwilai
authors.initials: R
authors.lastname: Samakoses
authors.affiliation: Kentucky Pediatric and Adult Research, Inc, Bardstown, Kentucky;
authors.forename: Stan L
authors.initials: SL
authors.lastname: Block
authors.affiliation: Center for Research in Population Health, National Institute of Public Health, Cuernavaca Morelos, Mexico;
authors.forename: Eduardo
authors.initials: E
authors.lastname: Lazcano-Ponce
authors.affiliation: Clinical Research Center, Medellín, Colombia;
authors.forename: Jaime Alberto
authors.initials: JA
authors.lastname: Restrepo
authors.affiliation: Primary Physicians Research, Pittsburgh, Pennsylvania;
authors.forename: Keith S
authors.initials: KS
authors.lastname: Reisinger
authors.affiliation: Coordinating Research Centre, Frederiksberg Hospital, Frederiksberg, Denmark;
authors.forename: Jesper
authors.initials: J
authors.lastname: Mehlsen
authors.affiliation: Department of Pediatrics, University of South Dakota Sanford School of Medicine, Sanford Children's Specialty Clinics, Sioux Falls, South Dakota;
authors.forename: Archana
authors.initials: A
authors.lastname: Chatterjee
authors.affiliation: Department of Obstetrics and Gynecology, Haukeland University Hospital, Bergen, Norway; and.
authors.forename: Ole-Erik
authors.initials: OE
authors.lastname: Iversen
authors.affiliation: Merck & Co., Inc, Whitehouse Station, New Jersey.
authors.forename: Heather L
authors.initials: HL
authors.lastname: Sings
authors.affiliation: Merck & Co., Inc, Whitehouse Station, New Jersey.
authors.forename: Qiong
authors.initials: Q
authors.lastname: Shou
authors.affiliation: Merck & Co., Inc, Whitehouse Station, New Jersey.
authors.forename: Timothy A
authors.initials: TA
authors.lastname: Sausser
authors.affiliation: Merck & Co., Inc, Whitehouse Station, New Jersey.
authors.forename: Alfred
authors.initials: A
authors.lastname: Saah
mesh_terms: D000293:Adolescent; D002648:Child; D004311:Double-Blind Method; D005260:Female; D005500:Follow-Up Studies; D052140:Human papillomavirus 11 / Q000187:drug effects / Q000502:physiology; D052162:Human papillomavirus 16 / Q000187:drug effects / Q000502:physiology; D052161:Human papillomavirus 18 / Q000187:drug effects / Q000502:physiology; D052163:Human papillomavirus 6 / Q000187:drug effects / Q000502:physiology; D006801:Humans; D008297:Male; D030361:Papillomavirus Infections / Q000097:blood / Q000453:epidemiology / Q000517:prevention & control*; D053918:Papillomavirus Vaccines / Q000008:administration & dosage* / Q000097:blood; D013997:Time Factors; D016896:Treatment Outcome; D014611:Vaccination / Q000639:trends*
chemical_list: D053918:Papillomavirus Vaccines
keywords: adolescents; anogenital cancer; effectiveness; genital warts; immunogenicity; quadrivalent HPV vaccine; safety