Health4Men: The science behind U=U


HIV-positive men on ART (antiretroviral treatment) with undetectable viral loads can’t pass it on to their negative partners – it’s been proven.

Eight years ago, 1000 gay couples were recruited for a revolutionary sexual health research project. The couples had to be ‘sero different’, meaning one was HIV-positive and the other HIV-negative and had to be already having condomless anal sex.

The study was to see what the rate of HIV transmission between these couples would be if the HIV-positive person was on HIV treatment (ARVs) and had an undetectable viral load. Together, these men from all around Europe recorded 77 000 acts of condomless anal sex. That’s a lot of sex!

And the results of HIV transmission? ZERO!

Not one HIV-negative partner was infected because the positive partner had an undetectable viral load due to sustained ARV treatment.

It was the second phase of another international research project called The Partner Study, which enrolled 1166 sero different couples (including heterosexual couples) who had condomless vaginal and anal sex. The results were also zero, which is what prompted researchers to launch the second phase known as The Partner2 Study, focusing exclusively on gay sero different couples.

In all cases where the HIV-positive partner was on ARVs and had an undetectable viral load, there was not a single HIV-negative partner that was infected.

The Partner2 Study was initiated because of the common belief that anal sex is a greater risk for HIV transmission, making men who have anal sex with men at greater risk.

The Undetecable equals Untransmittable (U=U) campaign advocates the effectiveness of correct long-term ARV treatment eliminating the risk of HIV transmission, which means that even if one partner is HIV-positive, the other is negative and they are having unprotected sex, the risk of HIV transmission is zero if the positive partner has an undetectable viral load.

Condoms are still an effective way to prevent the transmission of HIV and other STIs during anal sex, but condoms can occasionally slip off or break and this study really drives home the importance of HIV-positive individuals seeking out and adhering to ARV treatment in order to prevent the further transmission of the virus.

Another way that sero different partners can ensure that no HIV transmission can occur is if the negative partner regularly takes PrEP (Pre-exposure prophylaxis), which also prevents the possibility of HIV infection taking place by almost 100%. ARVs and PrEP may be very effective at preventing HIV transmission, but they do not prevent the spread of other sexually transmitted infections. Condoms are still the best line of defence for these.

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