Trends in testing of sexually transmissible infections (STIs), sexual health knowledge and behaviours, and pornography use in cross-sectional samples of young people in Victoria, Australia, 2015–21

Abstract

Background Sexually transmissible infections (STI) are prevalent and increasing among young Australians. This study examined trends in STI testing, sexual health knowledge/behaviours, and pornography use in young people aged 15–29 years in Victoria, Australia between 2015 and 2021. Methods Seven online cross-sectional surveys were conducted in a convenience sample of young people, recruiting a total of 7014 participants (67% female). Logistic regression analyses determined trends over time in binary outcomes. Results There was a decrease in reports of lifetime vaginal sex over time, while lifetime anal sex remained stable. Among those who had ever had vaginal sex, results showed an increase in the use of long-acting reversible contraceptives on the last occasion of vaginal sex. There was no change in STI testing or condom use with all partner types. Knowledge of STIs and sexual health changed over time: the proportion knowing that chlamydia can make women infertile decreased over time, while knowledge that taking the pill does not reduce fertility increased. There was no change in pornography use after adjusting for demographic variables. Conclusions Although uptake of long-acting contraceptives increased, STI knowledge and testing, as well as consistent condom use, remained low. Public health interventions should continue to address these critical components of STI prevention.