Between the crisis levels of HIV among African-American women in D.C. and the disease's impact on black gay men, the conversations taking place at this year's International AIDS Conference have been relatively grim.

It's been a big month for HIV advancements nonetheless, with the FDA approval of Truvada, the first pill proven to prevent HIV, earlier this month; the trial run of a new anti-AIDS vaginal ring that got underway this week; and reports on Thursday of two Boston men being cured of HIV by way of bone marrow transplants.

The question remains, however, what affect these breakthroughs, especially Truvada, might have on the effort to curb the epidemic among blacks. Dr. Warner Greene, president of Accordia Global Health Foundation and one of the leading presenters at the conference, said, "Could we prevent HIV infection in high-risk individuals by giving them Truvada? There have been now a number of clinical trials that have come to the conclusion that the answer is affirmatively yes."

There are, he said, some conditions. Greene recently explained to The Huffington Post how the anti-retroviral drug works and what he believes it will ultimately take for it to succeed.

Who are the most likely candidates for this treatment?
People who are particularly high risk: men who are having sex with men; if you're in a relationship with someone who is HIV positive; and people who have multiple sex partners. In the United States, being African American also puts you at higher risk for HIV infection. It's a sad but true statistic.

How exactly does Truvada work?
It's like a chemical vaccine. It's one pill a day -- a chemical blocker of a very early step in the HIV replication pathway, and highly effective blocker at that point. It's like a birth control pill.

What are the biggest barriers to the success of this drug?
There are problems from the point of view of cost. [Critics put the price tag around $1,200 per month.] But the worst thing would be taking it part of the time and having a sub-therapeutic level of drug on board and then becoming exposed to the virus. Intermittent use of the drug could lead to the emergence of resistance ... and then we'd lose two of our best anti-retrovirals.

Surprisingly, the pills were not taken as frequently by the subjects in the trials as we would have liked. [Only one in two of the men having sex with men who participated in the clinical trial took the pill as directed.] But if you took the pill, the protection was dramatic. [Those who did adhere to the directed dosage had a 90 percent rate of protection from HIV acquisition.]

How prevalent at this week's International AIDS Conference was the conversation around HIV prevention through drugs?
The world of HIV prevention has exploded. It started with the discovery that circumcision was about 60 percent protective in HIV transmission from women to men. Now ... treatment-as-prevention is clearly emerging very prominently -- treatment of high-risk individuals prophylactically -- but, even more so, treatment of HIV-infected individuals early to prevent them from spreading the virus to others.

I remember attending on the wards of San Francisco General Hospital in the early '90s when every patient I was caring for had AIDS, and there was nothing we could do for them. There are now very few patients with HIV infection in the hospital. They're all being managed as outpatients and many of them are doing very well.

All of this may buy us time until with get to the holy grail of an HIV vaccine.

What does this mean as far as curbing the HIV epidemic within the African-American community?
There's the issue of disparities of care in the African-American community, meaning that they're not accessing drugs early or as often, so the community viral load within the African-American population is cumulatively much higher. And that, of course, is what's driving higher level transmission. So we've got to get more African Americans into care, we've got to get the viral load down, we should certainly consider using pre-exposure prophylaxis in high-risk individuals, and we should be putting all of our prevention modalities in full force. That involves testing and counseling and condoms.

We have the tools now. There's no excuse.

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