The PARTNER study examines the risk of transmitting HIV when taking treatment (ART).
The second phase of the study, PARTNER 2, is now under way. It is currently enrolling male couples where one partner is HIV positive and the other negative. The positive partner will be taking ART to reduce virus in their body.
The study is running in the UK and 11 other European countries. The first phase of the study is already complete. This included both gay and straight couples. Phase 1 results reported in July 2016 demonstrated transmission risk was extremely low. Zero transmissions were reported within couples after more than 58,000 occasions of condomless sex. Results were from almost 900 couples, a third of which were gay men.
The second phase of the study is called PARTNER2. It focusses on following-up gay male couples who are not consistently using condoms. The intention is to gain the same amount of evidence for gay men as heterosexuals. It will run until 2018.