Inadequacy of ‘treatment as prevention’ strategy for combating HIV in young US MSM

The secret of containing the HIV epidemic is the successful engagement of key populations, we are told. In the case of the US that evidently includes young MSM (YMSM), amongst others.  The scale of the task that confronts public health interventions aimed at prevention in this group is brought out in a recent study by Wilson & Hightow-Weidmann  (W&H) who investigate the behavioural and social correlates of not achieving virological suppression.

If we take the HIV-infected population of the US as a whole, the relative impact on HIV onward transmission of the segment of the population that is infected, but not virologically suppressed (VL+), is critical to the control of the epidemic.  This is on account of the large proportion of total transmissions attributable to it.  One recent modeling study discussed in this blog (Skarbinski & Mermin {STI/blogs) (S&M)) has estimated the proportion of onward transmission attributable to VL+ at 61.3%, as against to 30.2% attributable to the undiagnosed.  (This model also takes account of the greater HIV infectivity of the non-virologically suppressed, through the impact of this is debated (Increased HIV infectivity (STIs/blog)).

So one can imagine the impact on onward transmission of failure to achieve virological suppression among YMSM, given that the proportion of HIV diagnosed who are VL+ is estimated by W&H at c.70%.  Further to this, W&H consider a factor that contributes an additional importance to the low level of viral suppression.  The headline statistic of their study is that the VL+ are considerably more likely to engage in risky sexual behavior than the rest.  Data obtained from the 20 US adolescent clinics that feature in the study show rates of condomless anal intercourse (CAI) for VL+ at 54.7%, as against 44.4% for VL-, and rates of serodiscordant CAI at 34.9%, as against 25%.  Other correlates of being VL+ are drug abuse, daily alcohol use and unemployment, suggesting a pattern or relative social marginalization that would tend to make this group harder to engage.

In their conclusions, W&H highlight the inadequacies of treatment as prevention as the sole risk reduction method.  A more underlying issue would seem to be retention in care and engagement with services, for socially marginalized populations.

Sherer (STIs) analyses the structural factors which make this particularly a problem for the US.  Access to sexual health services has been improved by the Affordable Care Act.  However, there remains considerable debate about how this will affect publically funded STD clinics which seem to have been financially squeezed in recent years.  Also about what role, if any, these clinics will continue to play in the US health system and what the implications of this will be for the accessibility of sexual health services for the socially marginalized (Mettenbrink & Cornelis (STIs); Stephens & Berstein (STIs); Hoover & Gift; Bocour & Shepard).