Using repeated, national, online, cross-sectional surveys of Australian gay and bisexual men (GBM), we analysed trends related to HIV pre-exposure prophylaxis (PrEP). Specifically, we analysed trends in PrEP use, willingness to use PrEP, and concern about using PrEP during 2011-2017. We assessed support for GBM using PrEP and willingness to have sex with men taking PrEP between 2015 and 2017. For time-based analyses, we used multivariate logistic regression, controlling for sampling variations over time. We constructed new scales assessing reduced concern about HIV among PrEP users and non-users in 2017, and used multivariate logistic regression to identify independent correlates of PrEP use (vs. non-use). The analyses included 4567 HIV-negative and untested participants (2011-2017). PrEP use increased from 0.5% in 2011 to 25.5% in 2017 (p < 0.001). Willingness to use PrEP increased from 27.9% in 2011 to 36.5% in 2017 (p < 0.001) while concern about using PrEP fell (52.1-36.1%, p < 0.001). Support for GBM using PrEP remained stable (52.5% in 2015, 51.9% in 2017, p = 0.62), and willingness to have sex with men taking PrEP increased from 34.9% in 2015 to 49.0% in 2017 (p < 0.001). In 2017, 22.8% of non-PrEP-users had reduced HIV concern because of PrEP, while 73.6% of PrEP users had reduced HIV concern and greater sexual pleasure because of PrEP. The analysis of PrEP users vs. non-users in 2017 indicated that PrEP users were more sexually active and reported higher risk sexual practices, were more likely to live in New South Wales and Victoria, and to be in full-time employment. They were also more likely to know HIV-positive people and other PrEP users. Diffusion of Innovations theory suggests that future PrEP users in Australia may be less adventurous and require greater reassurance about PrEP's efficacy and legitimacy, to sustain rollout and address current disparities in uptake.
Keywords: Acceptability research; Attitudes; Australia; Behaviour; HIV prevention; Pre-exposure prophylaxis.