A study of 343 gay couples, where one partner had HIV and the other did not, has not found a single case of HIV transmission in 16,889 acts of condomless anal sex, the 9th International AIDS Society Conference on HIV Science (IAS 2017) in Paris, France, was told today.

The Opposites Attract study looked at whether HIV is transmitted between gay male couples of different HIV status when the HIV-positive partner is on treatment that fully suppresses HIV. The HIV-positive partners in Opposites Attract had a so-called ‘undetectable viral load’ 98% of the time.

The study recruited and followed-up gay couples at clinics in Australia, in Bangkok and in Rio de Janeiro.

The evidence from Opposites Attract adds to the evidence from the PARTNER study that HIV-positive people on effective HIV treatment that fully suppresses their virus cannot transmit their infection through sex. Taken together, the two studies have not found a single case of HIV transmission in nearly 40,000 acts of condomless anal sex between gay men.

This adds further strength to the “U=U” (Undetectable equals Untransmittable) tagline of the Prevention Access Campaign, whose consensus statement has been signed by NAM and also by the International AIDS Society (IAS), organisers of this week’s Conference on HIV Science in Paris.

The studies also found that if the positive partner is on successful treatment, even having another sexually transmitted infection (STI) does not increase the risk of HIV being transmitted. In Opposites Attract, participants had an STI during 6% of anal sex acts and in PARTNER, 17.5% of participants had an STI at some point in the study. Read more via AIDSmap