Levels of HIV fall in Australia thanks to Treatment As Prevention (TASP)

Data presented at the Conference on Retroviruses and Opportunistic Infections (CROI 2020) this week has shown the impacts of Treatment as Prevention (TASP) on both new HIV diagnoses and community viremia (the number of people living with transmittable levels of HIV) in Australia. 

Dr. Denton Callander of the University of New South Wales presented the data at conference - much of which pre-dated the official rollout of Pre-Exposure Prophylaxis (PrEP) in the country.

“We’ve known for some time now that HIV treatment can prevent onward transmission of the virus at an individual level”, Callander said, referring to U=U (undetectable equals untransmittable),

“The question, however, is if this strategy can achieve ‘big picture’ public health goals, namely, to reduce new HIV infections.

"This study was created to try to answer that question by looking specifically at the relationship over time between ‘community viremia’ and new diagnoses of HIV among gay and bisexual men, the population most affected by HIV in Australia and many other parts of the world.”

Data for this study was taken from the ACCESS Australia database; a country-wide surveillance system that collects anonymous information about sexually transmitted infections among gay and bisexual men.

The study was conducted from 2012 to 2017 in the two most populous states of Australia: New South Wales and Victoria. Information was obtained from 67 institutions, including reproductive health clinics, hospitals, general practices, and community testing sites. In total, the study covered 115,982 men who have sex with men (MSM) [101,143 of them were HIV-negative and 14,839 HIV-positive].

Two measures were used to evaluate community-based viremia.

• Clinical viral load testing (indicating whether HIV-positive men had detectable or undetectable viral load (≤200 copies/mL)) from the ACCESS database.
• Estimated number of men with undiagnosed HIV, based on mathematical modelling, which assumed that they had a detectable viral load and, therefore, could transmit HIV.

The combination of parameters for HIV-positive men with detectable viral loads and the estimated number of people living with undiagnosed HIV can provide a reliable estimate of community-based viremia.

HIV incidence was established by analysing repeat HIV tests and new annual diagnoses for the period 2012-2017.

The correlation between viremia in the community and the annual incidence of HIV was calculated both before the widespread availability of PrEP in Australia in 2012-2015, and for the entire period from 2012 to 2017.

The study showed a significant decrease in active HIV viremia among diagnosed gay and bisexual men from 17% in 2012 to 4% in 2017, while the proportion of men living with undiagnosed HIV decreased slightly: from 11% to 9%.

“It’s an exciting finding with implications in many parts of the world, and it is one more reason for governments and health bodies to do everything they can to provide access to treatment for all people living with HIV,” Callander said.