title: Prevention of persistent human papillomavirus infection by an HPV16/18 vaccine: a community-based randomized clinical trial in Guanacaste, Costa Rica.
abstract: Target groups for human papillomavirus (HPV) vaccination are controversial. We evaluated vaccine efficacy (VE) against 1-year persistent infection, stratified by age and sexual behavior, among young women in Costa Rica. We randomized 7,466 healthy women 18 to 25 years of age to HPV16/18 or hepatitis A vaccine (follow-up, 50.4 months). According-to-protocol (ATP) cohorts included compliant HPV-negative women; intention-to-treat (ITT) included all randomized women. ATP VE was 90.9% (95% CI, 82.0-95.9) against HPV16/18 infections, 44.5% against HPV31/33/45 (95% CI, 17.5-63.1), and 12.4% (95% CI, -3.2 to 25.6) against any oncogenic infection. Overall ITT VE against HPV16/18 infections was 49.0%, but ATP and ITT VE almost reached 100% in year 4 of follow-up. ATP efficacy against HPV16/18 was similar by age, but ITT VE was greatest among youngest women (68.9% among those 18-19 years of age; 21.8% among those 24-25 years of age) and 79.8% among virgins. Among previously unexposed women, vaccination is highly efficacious against HPV16/18 and partially against HPV31/33/45. Vaccination is most effective in women and girls before they initiate sexual activity, with programmatic and individual decision implications.
authors.affiliation: Proyecto Epidemiológico Guanacaste, Fundación Instituto Costarricense de Investigación y Enseñanza en Nutrición y Salud, San José, Costa Rica. herreror@iarc.fr
authors.forename: Rolando
authors.initials: R
authors.lastname: Herrero
authors.forename: Sholom
authors.initials: S
authors.lastname: Wacholder
authors.forename: Ana C
authors.initials: AC
authors.lastname: Rodríguez
authors.forename: Diane
authors.initials: D
authors.lastname: Solomon
authors.forename: Paula
authors.initials: P
authors.lastname: González
authors.forename: Aimee R
authors.initials: AR
authors.lastname: Kreimer
authors.forename: Carolina
authors.initials: C
authors.lastname: Porras
authors.forename: John
authors.initials: J
authors.lastname: Schussler
authors.forename: Silvia
authors.initials: S
authors.lastname: Jiménez
authors.forename: Mark E
authors.initials: ME
authors.lastname: Sherman
authors.forename: Wim
authors.initials: W
authors.lastname: Quint
authors.forename: John T
authors.initials: JT
authors.lastname: Schiller
authors.forename: Douglas R
authors.initials: DR
authors.lastname: Lowy
authors.forename: Mark
authors.initials: M
authors.lastname: Schiffman
authors.forename: Allan
authors.initials: A
authors.lastname: Hildesheim
mesh_terms: D000293:Adolescent; D000328:Adult; D015331:Cohort Studies; D055812:Community-Based Participatory Research / Q000379:methods; D003364:Costa Rica; D005260:Female; D005500:Follow-Up Studies; D052162:Human papillomavirus 16 / Q000276:immunology*; D052161:Human papillomavirus 18 / Q000276:immunology*; D006801:Humans; D030361:Papillomavirus Infections / Q000276:immunology / Q000517:prevention & control* / Q000821:virology*; D053918:Papillomavirus Vaccines / Q000276:immunology / Q000627:therapeutic use*; D055815:Young Adult
chemical_list: D053918:Papillomavirus Vaccines