HIV epidemiology

Australia has a concentrated human immunodeficiency virus (HIV) epidemic, whereupon in 2018 sexual contact between men accounted for approximately 70% of new HIV diagnoses (1). During 2018, 23% of new diagnoses occurred in heterosexuals, and about one-third of these occurred where the person, or their partner came from a country with high HIV prevalence. Only 3% of new HIV diagnoses were attributable to injecting drug use alone.

Overall, the annual number of HIV diagnoses in Australia declined by 23% during 2014-2018 (1), and this decrease was attributable to a 30% decline in notifications among men who have sex with men (MSM). There was no decline in HIV in Aboriginal and Torres Strait Islander people (hereafter referred to as Indigenous), in heterosexual people or in those born overseas.

In MSM, an 11% decline in HIV notifications was observed over five years between 2013 and 2017, but the decline increased to 15% in 2016-2017. However, this decline in HIV diagnoses among MSM was not uniform. In the last 10 years, notifications declined by 21% in Australian-born MSM, while the proportion of notifications almost doubled (from 28% to 52%) among overseas-born MSM (1). The estimated proportion of undiagnosed HIV was also high among people born in Southeast Asia (27%) (1). The uptake of HIV preexposure prophylaxis (PrEP) remained low in this population, comprising only 9% of PrEP participants in the EPIC NSW trial (2). In Victoria, the incidence of HIV infection in newly arrived Asian-born MSM attending a sentinel sexual health clinic did not decline during 2013-2017 whereas the incidence fell by 45% in Australian-born MSM attending the same site (3).

A 10% increase in HIV notifications of heterosexual exposure was reported between 2013 and 2017, with a 14% increase between 2016 and 2017, which was mainly attributed to the increase in the number of notifications among Australian‑born men over these time periods (37% and 31%, respectively) (1). In women, the notification rate remained stable during 2013-2017 (between 0.7 and 0.9 per 100,000), however, was low compared with that in men (0.9 vs 7.1 per 100,000 in 2017).

In the Indigenous population the rate of HIV notifications increased by 41% between 2013 and 2016, compared with a 12% decline in Australian-born non-Indigenous people, and in 2017 was 1.6 times higher than in the Australian-born non-Indigenous population (1). During 2015–2017, more HIV notifications in the Indigenous population were attributed to heterosexual sex (21%) and injecting drug use (18%) than in the Australian-born non-Indigenous population (18% and 3%, respectively).

Among female sex workers, HIV incidence remained stable at or below 0.13 per 100 person-years during 2013–2017, and was 0.13 per 100 person-years in 2017 (1). Similarly, for people who inject drugs (PWID), HIV prevalence has remained low in the past 10 years and ranged between 1.0% and 2.1% among people attending needle and syringe programs (2.1% in 2017), and 0.7% if gay and bisexual men were excluded from the sample. However, prevalence of HIV among Indigenous men in these programs has increased almost five times between 2010–2011 and 2016–2017 from 0.9% to 4.2% (1).