We have tracked belief in the effectiveness of HIV treatment as prevention (TasP) among Australian gay and bisexual men (GBM) since 2013. National, online cross-sectional surveys of GBM were conducted every 2 years during 2013-2019. Trends and associations were analyzed using multivariate logistic regression. Data from 4,903 survey responses were included. Belief that HIV treatment prevents transmission increased from 2.6% in 2013 to 34.6% in 2019. Belief in the effectiveness of TasP was consistently higher among HIV-positive participants than other participants. In 2019, higher levels of belief in TasP were independently associated with university education, being HIV-positive, using pre-exposure prophylaxis, knowing more HIV-positive people, being recently diagnosed with a sexually transmitted infection (STI) and use of post-exposure prophylaxis. Belief that HIV treatment prevents transmission has increased substantially among Australian GBM, but remains concentrated among HIV-positive GBM, those who know HIV-positive people, and GBM who use antiretroviral-based prevention.
Keywords: HIV prevention; HIV treatment as prevention; U=U; attitudes; men who have sex with men.