The world’s largest study on HIV transmission has proved HIV+ men with undetectable viral loads cannot transmit HIV to their sexual partners.

The results from the Opposites Attract study were presented today at the IAS Conference on HIV Science in Paris.

Couples who participated in the study had different HIV statues – one of the men was living with HIV, while the other was HIV negative.

During the study, the men participated 17,000 acts of anal sex without a condom. None of those acts resulted in HIV transmission.

The University of New South Wales’ The Kirby Institute carried out the Opposites Attract study.

‘Undetectable virus level effectively prevents HIV transmission among gay couples,’ said the Kirby Institute’s Professor Andrew Grulich.

‘Opposites Attract is the first study to show that these results apply in both high and middle income countries.

‘Our research adds to the evidence from a small number of other international studies of heterosexual and homosexual couples and means that we can say, with confidence, that effectively treated HIV blocks transmission in couples of differing HIV status.’

HIV treatment works by suppressing the level of virus in a person living with HIV’s body. The treatment works so the immune system damage is halted and even reversed.

When treatment is consistently taken daily, the virus levels become so low that they become undetectable in the blood.

A life changing result

The results show when an undetectable viral load is maintained, the risk of HIV transmission is negligible.

‘This is life-changing news for couples of differing HIV status,’ said Grulich.

‘But it is important that the HIV positive partner is under regular medical care and does not miss any of their anti-retroviral medication in order to ensure they maintain an undetectable viral load.’

Opposites Attract involved 358 gay couples from Thailand, Brazil and Australia over four years from 2012–2016.

Stakeholders in the study included HIV/AIDS organizations in the countries where the couples lived. They argued this conclusive evidence will help end stigma for people living with HIV.

‘The results of the Opposites Attract study have important implications for serodiscordant couples in Brazil, and all around the world,’ said Dr Beatriz Grinsztejn from Brazil’s Evandro Chagas Clinical Research Institute.

‘Opposites Attract has shown us… an important finding that will help to break down stigma associated with living with HIV.

‘These results strengthen the argument for treatment as prevention and provide couples with options when it comes to negotiating safe sex.’