PARTNER was designed as an observational study estimating risk of HIV transmission. It observes couples with different HIV status who inconsistently use condoms. The positive partner will be taking effective ART medication.

Why is this issue important?

It is well documented that treatment reduces HIV transmission risk. However, there is little data about how low the risk actually becomes. The information currently available is mainly from heterosexual studies, providing limited data on anal sex. Many participants in these studies, including HPTN-052 (see study results), regularly used condoms.

Quantifying risk of transmission is important for two main reasons:

  1. To help reduce the risk of new infections.
  2. To understand the benefit of ART in reducing new HIV infections in the population.

Why is this study required?

Previous studies have not focused on people using condoms inconsistently. Nor have they provided much data on anal sex risk. Only 2% of participants (37 couples) in HPTN-052 were MSM (men who have sex with men). 96% of participants in that study reported regular condom use. For MSM, condomless anal sex is the major HIV risk factor, especially for receptive partners.

There are currently only two studies looking at HIV transmission in MSM/anal sex. These are the PARTNER study, and Opposites Attract (Australia). Many treatment guidelines already recommend starting ART at time of diagnosis to help reduce transmission. Data from studies like PARTNER is necessary to confirm these assumed benefits.