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It's MORNING EDITION, from NPR News. I'm Steve Inskeep.
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And I'm Renée Montagne. Good morning. This week marks an important turning point in the battle against AIDS. Yesterday, the Food and Drug Administration approved a pill that can drastically lower a person's risk of getting HIV - the first prevention pill for HIV.
It's not cheap. There's worry that people taking it might relax safe-sex precautions. But health officials hope it will help reduce the number of Americans who get HIV. Right now, that's around 50,000 people every year. NPR's Richard Knox has this look at who, exactly, should take the pill.
RICHARD KNOX, BYLINE: It sounds simple - a pill called Truvada, that can cut an uninfected person's risk of getting the AIDS virus by as much as 90 percent. But there are a bunch of complicated issues embedded in this new strategy.
DR. KEN MAYER: It's not just, you know, here's a pill; take it, and you're rendered protected.
KNOX: That's Dr. Ken Mayer of the Fenway Community Health Center in Boston. He's been researching the strategy for years. It's called pre-exposure prophylaxis, or PrEP. Mayer says there's one, very important thing people have to know before they start using Truvada.
MAYER: We want to be sure that when you're starting a person on PrEP, that they're not HIV-infected.
KNOX: Because Truvada alone isn't good enough to treat HIV. The virus could develop resistance to the drug if it's the only drug someone's taking. For the same reason, people on Truvada who are HIV-negative have to get re-tested for HIV every few months. Then people have to commit to taking the pill every day. If they don't, the protection drops off quickly.
Finally, people also have to keep using condoms and limiting their number of sexual partners, just as if they weren't taking the pill.
MAYER: So are people going to be numbed into a sense of security that they can have unprotected sex whenever they want, if they're going to be taking these medications? And the answer is, we just don't know.
KNOX: So far, the studies haven't found an increase in riskier behavior. All these issues are complicated enough that Mayer doesn't expect an avalanche of people using Truvada anytime soon.
MAYER: It's certainly not something for everyone.
KNOX: One group it may be for, are committed couples who are what doctors call "discordant" when it comes to HIV - one partner has it, the other one doesn't. Like James Callahan and Kevin Kirk.
JAMES CALLAHAN: I'm positive; he's negative. And I don't really know that we identify that way. But it's just a fact.
KEVIN KIRK: Yeah. I know from my end, I've never really put a lot of thought into it.
KNOX: They live in San Francisco and have been together for more than five years. Recently, they sat down with me and talked about whether Kevin, the HIV-negative partner, might want to take Truvada. At first, he was wary of the idea. But 40 minutes into the discussion, he said something that surprised his partner.
KIRK: That would make you sleep a little better at night.
CALLAHAN: It would?
KIRK: It would. Yeah. Yeah, I think so.
CALLAHAN: So if - say, some reason, you won a lottery, and you got to take the pill for free for the rest of your life; would you do it, just to be safe?
KIRK: Probably, yeah. Yeah, probably would.
CALLAHAN: Oh, interesting.
KNOX: As Callahan thought about it more, he began to warm to the idea, too.
CALLAHAN: If we didn't take the pill and you were to become positive someday, I would definitely say - you know - why didn't we? Why didn't we?
KNOX: They didn't make the decision on the spot. But they're definitely thinking about it. But in the bigger picture, Kevin Kirk isn't the most important kind of candidate to be taking Truvada for prevention. Callahan is on anti-viral treatment, which has lowered the amount of HIV in his blood to undetectable levels. Again, here's Dr. Ken Mayer.
MAYER: If you say to the person, is it possible that my partner could transmit HIV to me? The answer is yes, it's possible. Does it happen often? No, it would be exceedingly rare.
KNOX: It would be much more important, he says, to get Truvada to men and women who have a much higher risk of infection. They might live in places like Washington, D.C., where men have a 1-in-17 chance of getting infected and thus, are at risk of infecting their partners. Dr. Deborah Cohan says Truvada will really be important for women in such couples.
DR. DEBORAH COHAN: She is not particularly able to ensure condom use consistently. She does not have control in that way, in their sexual dynamics. He may or may not be on anti-retroviral therapy. But certainly, there's no way for her to force him to take those medications.
KNOX: So Cohan, a San Francisco obstetrician-gynecologist, has already been prescribing Truvada for such women. Individual doctors could do that because the drug's already in the market for treating HIV.
COHAN: The women for whom I've given Truvada are so immensely appreciative that they have some control over whether they get HIV or not.
KNOX: And there's a special group of heterosexual couples for whom Truvada will be a special boon - ones where the woman is uninfected, the man has HIV, and they want to conceive a child. Currently, the only safe way to do that is a complicated and expensive process. The man's sperm is treated so it's free of the virus. And then the woman's egg is fertilized in the test tube, and implanted in her uterus. Prescribing Truvada for her can avoid all that. Cohan says about 75,000 U.S. couples could benefit.
Richard Knox, NPR News.