Variations in HIV Prevention Coverage in Subpopulations of Australian Gay and Bisexual Men, 2017-2021: Implications for Reducing Inequities in the Combination Prevention Era.

Using repeated behavioural surveillance data collected from gay and bisexual men (GBM) across Australia, we assessed trends in HIV prevention coverage (the level of 'safe sex' achieved in the population by the use of effective prevention methods, including condoms, pre-exposure prophylaxis [PrEP] and having an undetectable viral load). We stratified these trends by age, country of birth/recency of arrival, sexual identity, and the proportion of gay residents in the participant's suburb. Among 25,865 participants with casual male partners, HIV prevention coverage increased from 69.8% in 2017 to 75.2% in 2021, lower than the UNAIDS target of 95%. Higher levels of coverage were achieved among older GBM (≥ 45 years), non-recently-arrived migrants, and in suburbs with ≥ 10% gay residents. The lowest levels of prevention coverage (and highest levels of HIV risk) were recorded among younger GBM (< 25 years) and bisexual and other-identified participants. Younger, recently-arrived, and bisexual GBM were the most likely to use condoms, while PrEP use was concentrated among gay men, 25-44-year-olds, and in suburbs with more gay residents. The use of undetectable viral load was most common among participants aged ≥ 45 years. Our analysis shows that high HIV prevention coverage can be achieved through a mixture of condom use, PrEP use, and undetectable viral load, or by emphasising PrEP use. In the Australian context, younger, bisexual and other-identified GBM should be prioritised for enhanced access to effective HIV prevention methods. We encourage other jurisdictions to assess the level of coverage achieved by combination prevention, and variations in uptake.