HIV treatment as prevention, as measured in community-level viral suppression, was strongly associated with a large drop in the number of new HIV infections among gay and bisexual men in Australia, even before PrEP was available. This study was presented by Dr Denton Callander from the University of New South Wales yesterday at the Conference on Retroviruses and Opportunistic Infections (CROI 2020).
Despite the clear benefits of treatment as prevention (or Undetectable = Untransmittable, U=U) at the individual level, no large-scale studies have yet evaluated the community-level effects of treatment as prevention (TasP) on direct measures of HIV incidence among gay and bisexual men. Previous research has indicated a disconnect between the benefits of TasP/U=U at the individual and population levels. Large observational and experimental studies carried out in various sub-Saharan African countries failed to show a strong link between rates of viral suppression and associated reductions in HIV incidence.
One of the challenges with the African studies is that they treated the population as homogenous rather than considering groups with different risk levels and uptake of treatment, including key populations such as men who have sex with men. Another challenge was defining the specific measures that would reveal a relationship between individual level viral suppression and its subsequent impact at a broader community level.