Sustained Decline in Hospitalisations for Anogenital Warts in Australia: Analysis of National Hospital Morbidity Data 2003-2020.

In Australia, school-based human papillomavirus (HPV) vaccination was introduced initially for girls in 2007, and then also for boys in 2013. While studies have shown declines in the incidence of anogenital warts, there is a paucity of recent data analysis assessing the impact of vaccination on more severe disease. The National Hospital Morbidity Database of the Australian Institute of Health and Welfare (AIHW) hospitalisation admission data that included ICD-10-AM code A63.0 ('anogenital warts') as the diagnoses, for the years 2003-2020, were analysed to estimate hospitalisation rates per 100,000 mid-year population. The annual average hospitalisation rates per 100,000 population for anogenital warts in both genders combined in the age groups 10-19 years, 20-29 years, and 30-39 years decreased, respectively, from 16.9, 49.6, and 23.6 in 2003-2007 (pre-vaccine period) to 2.6, 15.2, and 14.6 in 2008-2020 (post-vaccine period), equating to declines of 84.7%, 69.4%, and 38.2%, respectively. Following the introduction of the boy's vaccination, hospitalisation rates decreased further in the respective age bands from 4.3, 22.8, and 18.4 in 2008-2013 (early post-vaccine period) to 1.1, 9.3, and 11.7 in 2014-2020 (late post-vaccine period), equating to respective declines of 73.4%, 59.3%, and 36.4%. This analysis confirms that there is a substantial incremental decline in anogenital warts hospitalisations among Australians aged 10-39 years.