Study shows that HIV transmission can be effectively reduced through protective antiretroviral therapy for serodiscordant couples
New York - Researchers in China have shown for the first time that a large-scale public health programme providing antiretroviral therapy (ART) for the HIV-positive partners in serodiscordant couples (where only one partner is HIV-positive) has markedly reduced HIV transmission rates, according to an Article published Online First in The Lancet.
After the randomised controlled trial HPTN 052 showed in 2011 that ART treatment for the HIV-positive partner in a serodiscordant couple reduces sexual transmission of HIV, the World Health Organization (WHO) issued guidelines recommending that all HIV-positive partners in serodiscordant couples should be offered ART. However, until now, the real-world efficacy of this recommendation has never been tested.
A group of researchers led by Professor Yiming Shao, at the Chinese Center for Disease Control and Prevention in Beijing, examined data from China’s national HIV and epidemiology and treatment databases on over 38000 serodiscordant couples. Of these, 24057 couples had received ART at the start of the study period, while 14805 had not. Couples were followed for up to nine years (2003 2011), with the results of biannual HIV tests recorded alongside other data, such as age, educational attainment, and how the HIV infection had been acquired.
The scientists found that the rate of HIV transmission to the uninfected partner in the group that had received treatment was significantly lower than in the group that received no treatment, with ART for the HIV-positive partner conveying an overall 26% relative reduction in the risk of HIV transmission, compared to those without treatment.
This is the first time that ART for serodiscordant couples has been shown to have an effect on reducing HIV transmission rates in a real-world setting, vindicating the results of earlier trials, and demonstrating that this approach to reducing HIV transmission is feasible and effective in practice. However, the authors found that the protective effect of ART seemed to only last for one year, with transmission rates becoming comparable after the first year for both treated and untreated couples. They also noticed that the treatment as prevention was not effective when HIV-positive partners were injecting drugs or had very high CD4 cell counts .
According to Professor Shao, “These results substantiate the previous evidence from smaller observational studies and one randomised clinical trial that the treatment-as-prevention approach is a feasible public health prevention strategy on a national scale and in a developing country context. The durability and generalisability of such protection, however, should take account of the patient status. It’s possible that increasing rates of resistance to treatment in patients with high CD4 level, or decreasing adherence to treatment in patients injecting drugs, are contributing to the reduction in the protective benefit of treatment over time, but this, and other possibilities, will need further investigation.” 
Writing in a linked Comment, Professor Sten Vermund, at Vanderbilt University in Nashville, Tennessee, USA, describes the results as “encouraging”, but adds that, “For further insights, we must rely on research that is still in progress. Can community, regional, national, and international expertise and resources be mobilised to offer testing to all at-risk people at least yearly, link all infected people to care, and offer antiretroviral therapy to a much higher proportion of infected people than receive it at present, alongside expanded combination prevention activities? Can we ultimately reverse the HIV pandemic with the treatment-as-prevention approach, by offering antiretroviral therapy at coverage far greater than has been achieved up to now? Answers to these questions depend on rigorous research into implementation and programme deployment, so that we can succeed in bringing programmes to scale.”