VOA常速英語(yǔ): 研究支持特魯達(dá)瓦藥作為預(yù)防艾滋病的藥物

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New studies show programs that use antiretroviral drugs to prevent HIV infection are very effective. The findings were released at the Conference on Retroviruses and Opportunistic Infections in Seattle, Washington. (2/23-2/26)

Using HIV-suppressing drugs as a prevention method is called PrEP or pre-exposure prophylaxis. Supporters say it’s a powerful tool to help stop the spread of the AIDS virus.

Mitchell Warren, head of the AIDS advocacy group, AVAC, attended the conference, known as CROI.

“Over the last five years, there is a growing body of evidence that oral pre-exposure prophylaxis, or PrEP, is not just good therapy, but it’s good prevention. With the important caveat that like any effective drug it only works if you take it.”

Warren said three PrEP trials proved the effectiveness of Truvada.

“That is the combination pill of tenofovir plus emtricitabine. Most of the research has been around Truvada. It’s a well established drug. We know it’s a very safe drug. It was widely used in antiretroviral therapy for people infected. So, it was the first of the drugs that have been explored for PrEP. There are other drugs being studied for PrEP,” he said.

One of the trials is called the Partners Demonstration Project. It’s based on an earlier study in Kenya and Uganda of so-called “discordant” heterosexual couples. That’s where one partner is HIV positive and the other is not.

Warren said, “This was a project that enrolled new couples – a very large number of couples – in the two countries. And it was offering treatment to the HIV positive partner. But if the partner didn’t want to be on treatment – or if they were on treatment but not yet virally suppressed, which would give protection to their negative partner, as well – the PrEP was provided to the HIV negative partner as a bridge until the positive partner was virally suppressed.”

The study shows the use of PrEP reduced the risk of HIV infection by 96 percent.

Next, there’s the PROUD Study. It was done in Britain among high risk men who have sex with men, or MSM. All in the study were HIV negative.

“One of the important questions of the Proud Study was: would people change their behavior? You know, one of the big concerns over the last several years was that if everyone kind of ran to PrEP they abandon condoms. They would change their behaviors and be riskier. This was another piece of great news. It showed that there was an 86 percent reduction in risk among those people who were offered and took PrEP,” said Warren.

He said the Proud Study also shows there was a similar reduction in risk from other STIs or sexually transmitted infections.

The third – called IPERGAY -- took place in France and Canada. It enrolled MSM, who reported having frequent sex. It, too, shows an 86 percent reduction in risk.

“But this was a different study,” said warren, “They were trying to see if a different dosing schedule might also be effective. Rather than telling people to take it every day, what the participants in this trial were told was to take two pills within the 24 hour period before you think you might have sex. And if you do have sex, you should then take another pill 24 hours after having sex – and then another pill 24 more hours later. So, it’s basically four pills within three days.”

He said for the findings to have an effect in the real world, there needs to be an action plan that includes resources and research agendas. He says the focus should be on those “most at risk, especially young African women.”

“One of the things about science presented at CROI is that it’s often very elegant science, but it doesn’t have any impact on the epidemic if you don’t act on the science. The drug Truvada that is used for PrEP right now is only approved for use as prevention in one country, the United States. And there is an urgency -- and frankly a moral imperative -- that the drug get registered as a preventive tool in many, many more countries,” he said.

The AVAC leader cautioned PrEP is not for everyone. Efficacy trials continue for effective vaginal gels or rings containing antiretrovirals, as well as injectable ARVs taken every two to three months. Vaccine trials also continue.

Also at CROI, Doctors Without Borders released the findings of its HIV studies. The group, also known as MSF, said, “Among individuals not receiving antiretroviral treatment, men had twice the level of HIV virus in their blood as women at the same stage in the disease.” It says a high viral load greatly increases the risk of infection.

MSF said the findings help explain why incidence is so high among women – and that it could be critical to test and treat men even earlier. The studies were done in Kenya, Malawi and South Africa.