I'm Anne Rancourt for AIDS.Gov, and I'm here
at the National Institutes of Health with Dr. Carl Dieffenbach, director of the Division of AIDS at the National
Institute of Allergy and Infectious Diseases — part of NIH. Carl, thanks for being with us. It's a pleasure to be here with you.
So today we are talking to folks about viral
suppression and, in particular, about HPTN052; a study that looked at viral suppression. Tell us a little bit about this study. So, it's a really interesting study. Years ago, we asked the question — we wanted to answer the question:
would virologic suppression — meaning people who take drugs, the antiretrovirals, and fully suppress the
virus in their bodies: would they still be transmissible? Would their virus in their body be transmissible or would,
essentially, they be in a non-infectious state, and we designed the study by enrolling serodiscordant couples,
men or women, and either could be infected.
Then we put half of them on therapy, the other half not, and we waited
then to see with, in the presence of really the state of the art prevention packages being offered to both, what their
level of transmission was in the two groups. What we wanted to see was, was there lower transmission in the
treated couples? And, lo and behold, what we saw was that there was. There was a fairly significant effect. At the time of the interim analysis it was
96 percent effective blocking linked transmissions.
The recommendation from the data safety monitoring
board was to offer therapy to all the couples, not just the half that had been on
therapy. And in so doing, we were then able to start
asking a second important question, and that question was,
"Is therapy durable?" If you start therapy and you can sustain taking therapy 365 days a year every year and get
durable virologic suppression, is it maintainable over a period of time. Over the course of your lifetime, five years
is not really that long and, lo and behold, what we saw was the rate had dropped from 96 percent to 93 percent. So, by and large, Durable suppression and
the ability of these people to stay on therapy was proven to a
point where we were very pleased with the result that we had such a profound impact still on HIV transmission,
among these linked individuals.
Okay, all right. So, Carl, you mentioned a 96 percent reduction
in risk, which then turned into a 93 percent reduction in risk. What do those numbers mean? What is a reduction in risk? That's a really important question simply because you're dealing with sort of
the way a trial is set up. So, everybody counts in a trial, and so if
a transmission event occurs, regardless of why
it occurred, it counts against you as going toward risk.
And so what we saw by the end of the study: there were
cases where transmission had occurred in the early treated arm. But in subsequent analysis by the HPTN laboratories,
we were able to demonstrate that in each one of those cases the person who was on therapy in those partnerships
was not virologically suppressed. They had had a break in therapy for some reason, or they had not started therapy
soon enough. There was detectable virus in their systems.
So, you can talk about 96, 93. The important number is 100 percent because
if you were durably, virologically suppressed, you will not transmit to your
partner. I think that is one of the major takeaways
that we have to have from HPTN052. So, you can talk about 96, 93.
The important number is 100 percent because
if you were durably, virologically suppressed, you will
not transmit to your partner. I think that is one of the major takeaways that we have to have from HPTN052. I'll say this again. For somebody who is in a discordant couple,
if the person is virologically suppressed durably, there's
no virus in their system, hasn't been for several months, your chance of acquiring HIV from that person is zero.
Let's be clear about that; zero.If that person,
the next day, stops therapy for two weeks and rebounds, your chance goes
up. That's why viral — we talk about durable
virologic suppression. So you're as virologically suppressed as good
as your adherence. That's the message.
So as we go forward it comes back to how you as somebody in a serodiscordant
couple negotiate this. What is your role in helping to support, provide the adherence support for
your partner? What are the options that you can provide,
in terms of making sure that they take their pills, you
support them, and we move forward in society to honor and
support people who are playing these roles and continue to provide the assistance for both the HIV-positive
and the HIV-negative person in a discordant couple so that they can achieve their desired goals of living
and loving together. Thanks, Carl. And thanks for watching.
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