Antiretroviral therapy dramatically reduces HIV transmission
Richard Jefferys, TAG
A recent posting linked to the abstract of a study evaluating the impact of ART on HIV transmission that was presented at CROI earlier this year.
The full results have now been published in the Lancet.  The paper is generating considerable press coverage because the effect of ART was dramatic, equating to a 92% reduction in risk of transmission.
The study involved 3,381 couples in which one partner was HIV positive and the other negative. Out of 103 cases of transmission that were documented, 102 occurred in couples where the positive partner was not using ART. In the remaining case, ART had only very recently been initiated. Although the results represent the most compelling evidence to date that ART can reduce the risk of sexual transmission of HIV infection, its worth noting that the main purpose of the trial was to investigate the impact of suppressing herpes simplex virus infection with acyclovir on HIV transmission (these primary results have <http://content.nejm.org/cgi/content/abstract/NEJMoa0904849> already been published). The analysis of the effect of ART was thus post hoc meaning it was not pre-specified in the protocol (there is an ongoing trial called <http://www.hptn.org/research_studies/HPTN052.asp> HPTN 052 in which the primary endpoint is the impact of ART on transmission but results are not anticipated until 2014).
In an accompanying commentary in the Lancet, several scientists argue that these results call for rapid development of trials of a test and treat approach to reducing HIV incidence in which the main goal will be preventing transmission.  However the paper also makes it clear that transmission risk is highest among people who need ART for their individual health; given the stalling in funding to support treatment access globally, arguably the most important implication of the study is that this shortfall needs to urgently be addressed for reasons of public health, as well as to ensure the wellbeing of people with HIV who are currently being turned away from treatment programs due to lack of resources.
- Treatment reduces infections by over 90%: a theme that is here to stay. HIV Treatment Bulletin, April 2010. https://i-base.info/htb/10266
- Donnell D et al. The Lancet, Volume 375, Issue 9731, Pages 2092 – 2098, 12 June 2010. doi:10.1016/S0140-6736(10)60705-2. http://www.thelancet.com/journals/lancet/article/PIIS0140-6736(10)60705-2/abstract
- Dabis F, Newell M-L, Hirschel B. HIV drugs for treatment, and for prevention. Editorial comment. The Lancet. http://www.thelancet.com/journals/lancet/article/PIIS0140-6736(10)60838-0/fulltext
Source: TAG basic science blog. (27 May 2010). http://tagbasicscienceproject.typepad.com/tags_basic_science_vaccin/2010/05/the-impact-of-antiretroviral-treatment-on-hiv-transmission-risk.html