Treatment as Prevention: Undetectable is Untransmittable


Over the past few years, you might have heard a couple new phrases being used when guys talk about HIV prevention: ‘Treatment as Prevention’ and / or ‘undetectable.’ Both of these phrases refer to the same thing: when poz guys are on HIV treatment, their viral load can drop to the point that it might not even be detected by some kinds of HIV tests. This means they are HIV undetectable. It doesn’t mean that the virus isn’t present, just that it is present at such low levels it doesn’t even show up in some HIV tests. More importantly, though, when a guy is practicing TasP and undetectable, it means the virus cannot be transmitted, regardless of whether he is using other kinds of prevention tools like condoms or PrEP. Undetectable equals untransmittable! For more information on undetectability and HIV, check out this amazing resource from the Prevention Access Campaign's U=U campaign HERE.

Undetectable means different things in different places, but refers to the copies of the HIV virus that are present in a mL of an individual’s blood at the time of the test. In BC, undetectable refers to 40 copies of HIV per mL of blood, but in other places it is 50, or even 200. The number set in each jurisdiction is somewhat arbitrary, and is set differently because different jurisdictions may be taking more or less cautious approaches to HIV prevention. In a nutshell, we know more about the viral levels that CAN’T transmit HIV than the viral levels that CAN. When a guy is seroconverting to HIV, he might have millions of copies of the HIV virus in his blood, but this typically drops significantly even without medication. This number typically stays low for a number of years, before climbing again after the virus overwhelms the immune system. Until the development of HAART and TasP, this is the stage of illness when HIV clinically becomes AIDS. An individual with AIDS is a very sick individual; men still die of AIDS in Vancouver every year, despite the advances made through HAART and TasP.

Talk about ‘viral load,’ ‘copies of virus / mL’ and other scientific jargon can make undetectability more complicated than it is. Here are the facts, and your one key takeaway: guys using TasP who are undetectable DO NOT TRANSMIT THE HIV virus, regardless of the use of other prevention mechanisms. Some medical providers recommend using secondary prevention strategies like condoms or PrEP with undetectable partners, and some medical providers feel that TasP works fine as a standalone HIV prevention tool, especially for monogamous couples where one guy is neg and the other guy is poz. If you have questions about this, you can always call us at HIM, or contact the BCCfE for more information.

There have been two really important studies on undetectability over the past few years. The first one, HPTN 052, confirmed that undetectable individuals were 96% less likely to pass on HIV to a partner when having the kinds of sex where HIV can be passed. This study was groundbreaking, but had too few gay participants for it to be practically applicable to gay and bi guys, and other men who have sex with men. The second major study on TasP and undetectability, the PARTNER study, was more useful to gay guys because almost half the participants (40%) were gay couples. In the PARTNER study, all of the couples had to have condom-less sex at least some of the time, during the kinds of sex where HIV can be passed. The poz partner had to have a viral load below 200 / mL of blood, and had to be on-treatment and compliant (meaning they took their meds as directed) for at least five years. When the study completed, researchers announced that out of 16,400 sexual encounters where HIV could have been passed, not a single HIV transmission occurred. There were a couple HIV transmissions during the study, but when they analysed the virus in those participants, they learned that they had acquired it from someone other than the enrolled partner. Just like condoms and PrEP, it’s impossible to state that TasP and undetectability will work 100% of the time to prevent HIV transmission. That said, one of the study’s authors said it best: when she was asked what the study findings meant about the ‘real world’ chance of someone who is undetectable transmitting HIV, author Alison Rodger simply answered ‘our best estimate is it’s zero.’ And fellas, remember that your sexual health, and your needs and concerns, are your own. So remember to always use other prevention methods if you think you need them, and especially to help prevent contracting or transmitting other STIs.

Treatment as Prevention / ‘Undetectable’
Treatment as Prevention: Undetectable is Untransmittable
Did you know there’s a once-daily pill that can prevent #HIV transmission? #PrEP #GETPrEPED @HIMtweets