Final analysis of a study assessing genital human papillomavirus genoprevalence in young Australian women, following eight years of a national vaccination program.

OBJECTIVES: The VACCINE [Vaccine Against Cervical Cancer Impact and Effectiveness] study evaluated the prevalence of quadrivalent vaccine-targeted human papillomavirus (HPV) genotypes (HPV 6, 11, 16, 18) amongst young women of vaccine-eligible age.

METHODS: Between October 2011 - June 2015, women aged 18-25 years from Victoria, Australia, were recruited through targeted advertising on the social networking website Facebook. Participants completed an online questionnaire and provided a self-collected vaginal swab for HPV DNA detection and genotyping (Linear Array HPV genotyping assay). Self-reported HPV vaccination details were verified with the National HPV Vaccination Program Register (NHVPR).

RESULTS: Of 1223 who agreed to participate, 916 (74.9%) completed the survey and, for 1007 (82.3%) sexually-active participants, 744 (73.9%) returned the self-collected swab, of which 737 contained detectable DNA. 184/737 (25.0%) were positive for HPV. Vaccine-targeted HPV genotypes were detected in only 13 (1.7%) women: 11 HPV 16 (six vaccinated after sexual debut, five unvaccinated) and two HPV 6. Prevalence of any of HPV 31/33/45 collectively was 2.9%, varying significantly by vaccination status (fully 2.0%, unvaccinated 6.8%; p = 0.01). Vaccination rates among the sexually-active cohort were high, with 65.6%, 71.6% and 74.2% of participants having received three, at least two or at least one dose of vaccine, respectively. Of women self-reporting HPV vaccination, the NHVPR confirmed one or more doses were received in 90%. Strong associations were observed between vaccination status, age, language spoken at home and country of birth, as well as between HPV detection and the number of male sexual partners.

CONCLUSION: Surveillance five to eight years' post-initiation of a national HPV vaccination program demonstrated a consistent and very low prevalence of vaccine-related HPV genotypes and some evidence of cross protection against related types amongst vaccine-eligible women from Victoria, Australia.