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New HIV study shows treatment can deliver ‘zero’ risk of transmission

Home»New HIV study shows treatment can deliver ‘zero’ risk of transmission
05 Jun 2014
Media release • 6 March 2014

The National Association of People with HIV Australia (NAPWHA) has welcomed interim results from a large study indicating that an HIV positive person on successful HIV treatment poses virtually no risk of passing HIV onto their partner.

This study is the first to include a large number of gay couples where one partner is HIV positive and the other HIV negative. It therefore has particular relevance to Australia, where most people with HIV are men who have sex with men.

European researchers presented findings from the Partner Study at the CROI conference in Boston yesterday. This large study was conducted to look at whether people with HIV become non-infectious if they are on antiretroviral therapy (ART). After two years of the study, an interim analysis has found that there have been no cases where someone successfully taking HIV treatment transmitted HIV, either by anal or vaginal sex.

A previous study, HPTN 052, found in 2010 that the efficacy of HIV positive partners successfully taking HIV treatment was at least 96% in heterosexual couples, but had too few gay couples in it to establish if the same applied to them (or rather to anal sex). The Partner study was designed to address this gap in knowledge. It has so farrecruited 1110 couples where the partners have differing HIV status – and nearly 40% of them are gay couples.

Statistical analysis shows that the maximum likely chance of transmission via anal sex from someone on successful HIV treatment was 1% a year for any anal sex and 4% for anal sex with ejaculation where the HIV-negative partner was receptive; but the study presenter Dr Alison Rodgers of the UK said that the true likelihood is probably much nearer to zero than this.

When asked what the study tells us about the chance of someone taking HIV treatment successfully transmitting HIV, study presenter Alison Rodger said: "Our best estimate is it's zero."

Robert Mitchell, President of NAPWHA said “These results provide further evidence of the powerful impact that HIV treatment has on preventing HIV transmission. It is important that every effort is made to alert people with HIV and their doctors to these latest findings, particularly as this study is the first of its kind to include a significant number of gay couples.


Rodger A et al. HIV transmission risk through condomless sex if HIV+ partner on suppressive ART: PARTNER study. 21st Conference on Retroviruses and Opportunistic Infections, Boston 2014. Abstract#153LB. 2014.

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