Treatment as prevention: will it work?

In the past two years, rapidly emerging new trial results have provided the scientific community and people living with human immunodeficiency virus (HIV) or acquired immune deficiency syndrome (AIDS) or at risk of infection, with welcome news. Interesting scientific evidence is accumulating for the effectiveness of biomedical interventions to prevent the transmission of HIV. Infected people may become less contagious when the viral load is suppressed by antiretroviral therapy (ART). In 2010, results from the Pre-Exposure Prophylaxis Initiative (iPreX) randomised controlled trial provided the first evidence that antiretroviral pre-exposure prophylaxis can reduce HIV incidence. In their study, Grant et al showed, that that daily oral antiret-roviral medication reduced HIV incidence in HIV negative men who have sex with men (MSM) by 44% [1]. In July 2011, two studies from the United States, the TDF2 (tenofovir disoproxil fumarate and emtricitabine (TDF)) study and the Partners Pre-exposure study provided evidence that a daily oral dose of antiretroviral medication can reduce HIV acquisition among uninfected individuals exposed to the virus through heterosexual sex by at least 60% [2-3]. The randomised controlled HIV Prevention Trials Network study (HPTN 052) by Cohen et al demonstrated that earlier treatment (time of enrolment in study compared with CD 4 cell counts within or below 200-250 cells/mm 3 or developing an AIDS defining illness) of HIV-infected persons with ART had both a clinical benefit for the infected individual and resulted in a 96% reduction in transmission to the uninfected sexual partner [4]. Early treatment for HIV, prevention of mother-to-child transmission, post-exposure prophylaxis, male cir-cumcision, consistent condom use, behaviour change communication, microbicides, and possibly targeted pre-exposure prophylaxis are the most effective tools to prevent HIV transmission on individual and population levels [2-6]. Mathematical modelling studies indicated that early testing and early treatment of all individuals with HIV could effectively halt HIV transmission at the population level. Ecological studies have confirmed the effectiveness of the test and treat strategy in reducing HIV transmission and it appears to be bolstered further by HPTN 052 trial results [7-11]. New data on HIV in Europe in this issue by Likatavicius and Van de Laar demonstrate that HIV remains a public health problem in the European Union (EU) and European Economic Area (EEA) where more than 27,000 newly diagnosed HIV infections were reported during 2010 [12] (an increase of 4% compared with 2009). HIV diagnoses among men who have sex with men (MSM) have …