Transcript: Prevention Highlights Part 2 - Treatment as Prevention

April 12, 2009

At the 16th Conference on Retroviruses and Opportunistic Infections (CROI) in Montreal, Tim Horn talks with Sharon Hillier, PhD, from the University of Pittsburgh, about the latest in prevention science. Part 2 focuses on the notion of treating people with HIV as soon as they test positive as a way to prevent HIV transmission on a community-wide level. Click here to view the video.

Tim Horn: Hi, this is Tim Horn, the Editor-in-Chief of AIDS MEDS.com and I am here with Dr. Sharon Hillier of the University of Pittsburgh School of Medicine. This is the second of our two-part interview discussing biomedical approaches to prevention. In the first part of this interview we talked about some of the issues with pre-exposure prophylaxis or PrEP.  In this segment I very much wanted to talk with Dr. Hillier about anti-retroviral therapy, mostly in those who are currently infected with HIV and how that potentially benefits in terms of prevention.

Let’s start by talking about a presentation that took place here on Sunday afternoon. Christophe Frazier of the Imperial College of London gave a fascinating talk on the effects of anti-retroviral therapy and transmission. A key argument was that with universal HIV testing and universal treatment, basically getting everyone who is positive onto treatment as quickly as possible, this will have a tremendous impact on transmission rates of HIV. I’m just wondering if you could talk a bit about that.

Sharon Hillier:  It’s a really exciting notion that has come into the HIV prevention area: the notion that we could potentially screen everyone, identify who’s infected, put them on treatment, and by then controlling the virus drive the transmission down. That is to say, by treating infection, you stop transmission.  And so this is called the screen and treat. And it’s become a mantra among many quarters as a simple way, a simple model, to stop HIV.   The idea of screen and treat is an important one, and it sounds simple, but there’s a lot of difficulty in how it might be implemented.  So I think it’s getting a lot of important scientific review these days and I think there needs to be a lot of discussion to find would it really work if it were rolled out in the United States and internationally.

TH:  I think that whole concept really served as the basis of a big statement in Switzerland by a number of researchers there that really reducing the viral load to undetectable levels, I think they had put it as a no risk, but I think people are really thinking of it rather as a low risk of transmission. Okay, now let’s just back up a bit a second. When we’re talking about universal testing, and a screen and treat, universal testing and effectively making everyone who is tested aware of their status, and I’m just thinking that that in itself is a very important component to this.  The fact is that we do see that a number of people, and most people who do find out of their status, even with a little bit of counseling, they are going to take the necessary steps to keep the virus to themselves, to not pass the virus forward, so I’m just wondering can we achieve a great deal of prevention and to achieve these goals of really slowing and halting transmission of  the virus through universal testing without necessarily having to put everyone on treatment immediately, which certainly has a great deal of validity in parts of the world where treatment isn’t universally available yet to everyone who is infected.
 
SH: You bring up a lot of really good points; could we do a lot just by increasing screening and knowing your status.  I know in my town, Pittsburgh, we have a Know Your Status campaign where advocates in our community go door to door in buildings and businesses and ask everyone to accept an HIV test because knowing your status empowers you to make changes in your own behavior.

TH: Sure.

SH: So I think we haven’t done very well in the United States yet, even though we have recommendations for more universal screening, that hasn’t been accomplished. So I think you’re exactly right; we need to accomplish that goal first, in the United States and Europe and in the world to have better acceptance of screening. I think the next question is could we then harness the resources, the capacity, the infrastructure, to make treatment more broadly available.   Again, a really important goal, one that’s going to be very difficult to achieve, and I think a doable first step is to really increase the acceptance of screening and giving good counseling allowing people to act on their own to modify their behavior to empower themselves with that information to get health care when they decide they are ready for treatment.

TH: In your experience as a clinician and as a researcher do you find that patients of yours, for example, who do find out that they are positive, when they find out that they are positive, that many, most if you will, do take the necessary steps, or at least tell you that they take the necessary steps to stop the forward transmission of the virus?

SH: As a researcher, and I am a researcher, what we learn in our studies is that people who find out that they are infected, after they can begin to accept that information, do act and want to, in the women, the populations that we work with, really concerned how to protect their children, how do they protect their partners, so I think there is a powerful force to be harnessed just in extending screening.

TH: Absolutely, absolutely.  There is no doubting the profound effect that treatment can and does have on transmission rates.  I think we’ve seen a few studies here that have shown that, certainly in Uganda we’ve seen that repeatedly from the same study that the lower the viral load, the lower the risk of transmission.  However, that begets another issue, and something that was quite a focus here, which is the issue that one can have an undetectable viral load, however there seems to be evidence that in someone who does have an undetectable viral load in their blood can in fact have detectable virus in their semen, as well as in like let’s say the other female genital tract, whether it be the cervix or in the vagina.  I’m wondering if, number one, you could talk about that just a little bit and also if you could think about it contextually, like how concerned do we need to be regarding those research findings?

SH: Well, it’s really an interesting set of papers that were presented at this meeting, Tim, and really I think bring up that very critical question; how safe are you once you are fully controlled in terms of having your viral load under control, undetectable systemically in the blood.  Are your genital secretions free of virus, that’s really the key question. Two studies presented at this meeting, one from France, one from Canada, both showing exactly the same thing, that even though the virus is completely undetectable in the plasma, we’re still finding that some people are shedding virus in the genital tract. And so that means that even though a man has perfectly good control he could still infect his partner by shedding virus. The risk is lower, there’s no question, but it’s absolutely true that it could happen.  The investigators showed that the virus that was present in the semen of these men with perfect viral loads still was infectious.

TH: Question on that: do we have a sense of what the prevalence is? Or let’s say what percentage of men or women who have undetectable viral levels in the blood may have detectable virus in their semen or in their genital tract?   Is that possible?

SH: Well, it’s a little bit tricky. It seems like an easy question to answer but not so easy, because what we’ve learned about viral shedding in the genital tract in both men or women is that it’s not on or off.  It’s on some days, on maybe even some parts of some days, and then off. So the real

TH:  That’s very interesting.

SH: The really critical thing is not that you’re a shedder or a non-shedder. In the context of good viral control, systemically, what we see is that small things can actually increase shedding locally, and it’s not necessarily predictable. And so it’s not as often. If someone has an acute infection or high viral load systemically, no question, they are more likely to be shedding virus all the time. But there are sporadic episodes of shedding. And in some people it’s not completely predictable, and that I think unpredictability is what makes it hard for HIV infected people to decide when might it be safe. Same sort of story with women. Even though women have had good viral control with systemic therapy, no detectable virus in the plasma, we can still see genital shedding.  More often sometimes if women have genital infection, yeast vaginitis, and many other typical kind of infections, and yet it’s not always predictable. So I think the lesson for people is that getting your viral loads down is great, but having no detectable virus systemically does not mean that you are not shedding virus genitally.
  
TH: Which I guess raises the issue again, do you or don’t you take off the condoms, what have you, so, very interesting, and I think we can all look forward to more data regarding those particular findings. Dr. Hillier, thank you very very much for joining us.

SH: Thanks so much, Tim.

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