HIV prevention through HAART: a victim of its own success?

A recent study (Kalichman & Allen (K&A)) involving a series of four cross-sectional surveys (1996-2016) at a Gay Pride event in US Atlanta Georgia adds to the mounting body of evidence that substantial changes have occurred in community-held beliefs about the safety of certain sexual behaviours in the era of HIV treatment as prevention.

It might seem surprising, in view of the known effectiveness of ART as a preventative tool, that its deployment has generally failed to deliver the preventative benefits that might have been anticipated.  It is essential to achieve progress right along the ‘treatment cascade’, including, not only access to testing, but integration into treatment and viral suppression, for those benefits to be realized.  The fact remains that levels of infection amongst MSM, even in countries that have scaled up testing and treatment, have remained stable or are actually rising.

The obvious hypotheses, tested by K&A in this study, are that, 1., the perception of safety on the part of MSM has led to an increase in condomless anal sex, and that, 2., the growing incidence of STIs resulting from these sexual practices has itself had a direct impact in reducing the protective effects of ART.  (Of course, this is not to deny that sizeable proportion of the MSM community in the US – as in Australia (Mao & de Wit) – be successfully engaged in deliberate HIV risk-reduction strategies.)  The four surveys adopted identical measures and procedures, and involved ascertaining proportion of condom use during anal intercourse and number partners over the previous six months as well as assessment of beliefs regarding the preventive effectivess of ART (nine items of the questionnaire).

Results were as follows.  For HIV negative men: condomless anal sex (CAS) increased from 43% (1997) to 61% (2015); reporting two or more condomless sex partners from 9% to 33%.  For HIV positive men:  CAS from 25% to 67%; reporting two or more condomless sex partners from 9% to 57%.  As regards beliefs that ART was protective, comparisons across survey times indicate a main effect for year of survey, F(3, 1829) = 6.3,p<0.01, with an effect across survey year for men who engaged in CAS, F(1,1829) = 9.3,p<0.01.  Most evident from figures is a precipitous drop in perception of risk amongst both groups between the third and fourth survey (2006 and 2016).

K&A’s hypotheses (one or both) would seem to be corroborated from another quarter by the observed association with the introduction of HAART of an increased infection rate of gonorrhoea and syphilis (Stolte & Coutinho (STIs)) and of viral STIs (de Laar & Richel (STIs)).  Indeed rates of MSM syphilis increase coinciding with HAART introduction have been so dramatic in some places (e.g. Buenos Aires (Bissio & Cassetti (STIs)) as to lead to a hypothesis that HAART agents may actually be impairing immunity to the virus (Rekart & Cameron (STIs); Tuddenham & Ghanem (STIs)).  Whatever the validity of the latter hypothesis, evidence of STI epidemics is consistent with evidence of attitudinal and behavioural changes, such as those proposed by K&A.

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