Genital warts trends in Australian and overseas-born people in Australia: A cross-sectional trend analysis to measure progress towards control and elimination

Background: Substantial declines in genital warts have been observed in countries with quadrivalent/nonavalent human papillomavirus (q/n HPV) vaccination programmes, with Australia showing the most pronounced and long-term reductions. No study has assessed progress towards elimination of genital warts in a nation-wide sample of patients, and migrants’ contribution to population-level control of genital warts. We assessed Australia's progress towards genital warts elimination by examining trends in diagnoses in Australian- and overseas-born patients of sexual health clinics (SHCs) across Australia. Methods: A cross-sectional trend analysis of new genital warts diagnoses among first-time patients of 34 SHCs, between 2004 and 2018, was performed. Rate ratios (RR) were calculated using Poisson regression models, for comparing trends in proportions of new genital warts diagnoses in Australian- and overseas-born patients during the pre-vaccination era (2004-2007) and the vaccination era (2008-2018), and by 2018 relative to 2004-2007. Findings: A total of 439,957 new patients (Australian-born: 230,230; overseas-born: 209,727) were seen at SHCs, 6•4% were diagnosed with genital warts (Australian-born: 7•1%; overseas-born: 5•6%). By 2018, there had been a 64% reduction in the proportion of all SHC patients with a genital warts diagnosis relative to 2004-2007 (RR: 0•36, 95% CI: 0•35-0•38). The decline was more pronounced at 72% (RR: 0•28, 95% CI: 0 •27-0•30) among Australian-born patients, with the greatest reduction in women and men aged <21 years, at 98% (RR: 0•02, 95% CI: 0•01-0•03) and 92% (RR: 0•08, 95% CI: 0•06-0•11), respectively. By 2018, there was a 49% reduction in the proportion of overseas-born patients diagnosed with genital warts (RR: 0•51, 95% CI:0•48-0•54), and a 21% reduction in overseas-born patients from countries with no or bivalent HPV (bHPV) vaccination programme (RR: 0•79, 95% CI: 0•71-0•90). Interpretation: The substantial reductions in Australian-born people is a testament to the efficacy of quadrivalent (qHPV) and nonavalent (nHPV) vaccines and the high and wide-spread vaccination coverage in Australia. However, population-wide elimination of genital warts in Australia is dependent on other countries initiating or expanding their own HPV vaccination programmes. Funding: The Australian Government Department of Health and Seqirus Australia.