A Promising Game-Changer In HIV Prevention

Originally published on July 19, 2011 12:05 pm
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MICHEL MARTIN, host: I'm Michel Martin and this is TELL ME MORE from NPR News.

Coming up, we've been following many of the tough choices many cities and states are making as they try to manage shrinking resources. In Los Angeles, the budget for summer school was slashed by millions of dollars this year. We'll try to find out what these cuts mean for parents and students. That conversation in a few minutes.

But first, there is news of a possible breakthrough in HIV/AIDS prevention coming from the International Aids Society Conference that is meeting in Rome this week. A drug called Truvada prevented the transmission of HIV in more than 60 percent of patients during trials among heterosexual partners in Botswana.

Dr. Michael Thigpen led this study. He's a medical epidemiologist from the Centers for Disease Control and Prevention. And he's with us now from Rome, where he is taking part in this conference. And I do want to mention that this conversation will touch on sexual matters, so that might not be appropriate for everyone. With that being said, Dr. Thigpen, welcome. Thank you for joining us.

Dr. MICHAEL THIGPEN: Well, thank you very much for having me.

MARTIN: It's worth noting that yours was one of two promising studies on anti-retroviral medications that's being presented at the conference. Could you help us understand what is it that researchers are so excited about?

THIGPEN: Well, these particular medications, the drug Truvada specifically that both our study as well as another study conducted by the University of Washington found that while these drugs have been used for many years for treating people with HIV, we now have shown through two very strong studies that these drugs can also be used for people who are HIV negative to prevent themselves from getting HIV.

MARTIN: How was your study conducted?

THIGPEN: We enrolled 1,219 people in Botswana and they were randomly assigned to either receive Truvada or a placebo to be able to see whether Truvada was safe and effective for preventing HIV. And we would monitor them monthly to see whether they were would become infected with HIV as well as provide them a very comprehensive package of services to be able to protect themselves even better.

So, we would give them a lot of counseling, condoms, and medical care that would help them as well to be able to protect themselves from getting HIV. And despite these particular services, we found that Truvada protected an additional 63 percent of people from getting HIV who were taking the study medication.

MARTIN: Well, we've I think many people who follow this have heard about the ABC method of prevention abstinence, be faithful, use condoms. So, do I understand this properly that this adds to the tool kit of possibly other methods that one could use in addition to abstinence, being faithful, and using condoms?

THIGPEN: Absolutely. And this particular approach and other prevention strategies would not be used in isolation. We would not want people to stop doing those things that have been shown to be to reduce one's risk of getting HIV - being faithful to your partner, using a condom each and every time.

But there still continue to be times when people may forget to use the condom correctly or the condom may break or other times when they put themselves at risk for HIV. And so, using Truvada as what we call pre-exposure prophylaxis, where you would take a medicine before you're exposed to in this case HIV could potentially prevent substantial numbers of people from getting HIV.

MARTIN: Well, I understand that HIV rates among women in Africa continue to remain higher than among men. And I understand that the rates in Botswana are among the highest in the world. First of all, why is that? And why is this important given that women are more likely to be exposed than men?

THIGPEN: You're exactly right. Rates among women in their 30s in Botswana, approximately 50 percent of women age 30 to 39 years of age has become HIV infected. And so, women continue to bear the brunt of the HIV epidemic throughout much of Africa.

And that's where our approach really is able to provide women with a tool that they can use to protect themselves. Their husband may not want to use a condom or they may not know their partner's status. And this will allow the woman to be able to use Truvada to protect herself from getting HIV.

MARTIN: Which doesn't require her to negotiate with a partner who may not be as cooperative as would be necessary to really be safe.

THIGPEN: Exactly.

MARTIN: But I think the question - and I think a couple of questions arise here - which is how much does this cost? I mean, one of the points that I think some people make is that, you know, condoms are affordable. This drug can't be as affordable as a condom, can it?

THIGPEN: No, no. That's something that each individual government, looking at their particular epidemic, will need to decide in terms of whether it's worth the cost of investing in this type of prevention strategy.

To their credit, the manufacturer of this drug, Gilead Sciences, has released the intellectual property for manufacturing this medication to several other companies in India and South Africa and other places to be able to make generic versions of the drug, which will reduce the cost of manufacturing to - some estimates are about 25 cents per pill.

So, it makes it more cost effective. But in this time of limited resources, it's really going to be incumbent on each individual country to look at how best to direct their resources to prevent the epidemic.

MARTIN: How often do people have to take this drug for it to be effective? Do they have to take it every day, one pill a day, two pills a day, every day for the rest of their lives?

THIGPEN: What we looked at was looking at it where people would take a pill once a day. And that was similar in the other studies that I mentioned earlier by the University of Washington. But there is some preliminary evidence, especially among animal models suggesting that perhaps just twice a week and after sexual intercourse may be sufficient.

So, there are other studies ongoing, which are looking at how best that this medication could be taken. And if the medication was found to be effective at less frequent dosing that would also reduce the cost of this approach.

MARTIN: You know, there are those who, you know, we've had this debate in this country over other medications. There are those who fear that if you offer something like this that people, you know, will become less likely to participate in those other methods.

Like, for example, there's a debate around Gardasil in this country, which is designed to prevent cervical cancer and, you know, young women have to take it. They have to take, you know, a number of shots. And there are those who object to young women being encouraged to take these shots because they feel that it would then encourage them to be less mindful of their sexual habits.

But does anyone say - has anyone said that making it widely available would encourage people to be less careful about their sexual practices, which are still important?

THIGPEN: And that is a concern which we looked at during the context of our study, as did the other investigators. And we found that in conjunction with providing risk reduction counseling, information to our participants, our patients to better inform them about how to protect themselves from getting HIV in general, including condom use that actually people were less likely to have high-risk sexual activity even if they were not taking the study medication.

And so, well, the next steps will be since this was a research study to look at how people would react more in the real world with projects, including one which we will be conducting in Botswana, among our participants, providing them, for their benefit, the study medication Truvada for 12 months. During which time, we'll continue to monitor their behavior and provide them this risk-reduction counseling.

And so it's really going to require our approach as well as any HIV-prevention approach, whether it be male circumcision, female microbicides, or other types of interventions to be as part of a larger package of risk reduction strategies, including being faithful and condom education.

MARTIN: How long have we, and by we I mean you, been looking for something like this? How long has this search for a prevention tool, another prevention tool been going on?

THIGPEN: Oh, for many, many years. We, just four years ago, had very few tools in our toolbox. Other than being faithful and condom education, there was very little that we could do to be able to prevent HIV. Four years ago, the first study showing that male circumcision would reduce HIV infection among men by more than 50 percent. And that was very important because now we had an approach that could be used.

But we didn't have approaches which could be used by women. And so that's why our study, as well as the study last year, which showed that a vaginal gel could protect women from getting HIV, why these results are so exciting and really add to the number of different approaches we have to be able to prevent HIV.

MARTIN: Well, of course you're a scientist so I'm hesitant to ask for emotion, but I will try.


MARTIN: And just say, well, how excited are you about these findings after having worked on this for so long?

THIGPEN: Oh, this is really a great day in HIV prevention. Our study, as well as the Partners PrEP Study, conducted by the University of Washington, really adds to the growing evidence that we can, by using anti-HIV medications, really can prevent HIV infection and significantly so.

Both of our studies found that greater than 60, 70 percent of men and women could be prevented from getting HIV by using this approach. So we're all extremely excited. We're ecstatic that this really is a game changer and could turn the tide of the HIV epidemic in much of the world.

MARTIN: Dr. Michael Thigpen is a medical epidemiologist from the Centers for Disease Control and Prevention in Atlanta. We caught up with him in Rome, where he is taking part in the International AIDS Society Conference. Thank you so much for joining us.

THIGPEN: Oh, thank you so much for having me. Transcript provided by NPR, Copyright NPR.