Giving both pre-exposure prophylaxis (PrEP) and antiretroviral therapy (ART) to heterosexual couples where one partner has HIV (serodiscordant couples) can almost eliminate the chance of infection in the HIV-negative partner, a study presented at the Conference on Retroviruses and Opportunistic Infections (CROI 2015) in Seattle, USA, yesterday has shown.
This study was a first in a number of ways. It is the first to combine the ideas of PrEP and of ‘treatment as prevention’ in a systematic and sequenced way. It is the first large study in Africa to use a ‘risk score’ specifically to target the intervention to those most at risk of HIV. And it is the first study of treatment as prevention to document near-elimination of HIV transmission not just from the HIV-positive partner in a serodiscordant couple, but also from extramarital partners.
The Partners Demonstration Project (PDP) is being run in Kenya and Uganda in four centres that had hosted the Partners PrEP study, which demonstrated high levels of effectiveness for PrEP within serodiscordant couples. It is an ongoing project which will not finish until December 2016.
None of the 2026 participants (1013 couples) in the new study had been in Partners PrEP, and all were new to antiretroviral therapy, whether taken as treatment or PrEP. In two-thirds of couples, the female partner was the one who had HIV.
The Partners Demonstration Project combines PrEP and ART with the idea of using PrEP as a ‘bridge’ to fully suppressive ART in the relationship. The HIV-negative partner is offered PrEP as long as the HIV-positive partner is not on ART, and also for the first six months the HIV-positive partner is on ART. The six-month overlap period gives time for the person starting ART to become undetectable, but can be extended if adherence is known to be poor.
The HIV-positive partner is offered ART in accordance with national guidelines. At the start of the study, in November 2012, both Kenyan and Ugandan national guidelines recommended that ART be started at a CD4 threshold of 350 cells/mm3. In the second half of 2013, in accordance with WHO guidelines, both countries switched to offering ART immediately upon diagnosis to people with HIV who were in a serodiscordant relationship. The data presented cover the period from November 2012 to August 2014.