AIDS researchers are excited — to use their word — about two new studies that seem to nail down the effectiveness of a daily antiviral pill to protecting heterosexual men and women against HIV.
Among 6,000 young people in Kenya, Uganda and Botswana, those who got a pill containing one or two antiviral drugs had 63 percent to 73 percent less risk of getting HIV over a year. Among those whom researchers think took the pill most faithfully, the risk was almost 80 percent less. And the regimen appears safe.
"It's very good news," Dr. Julio Montaner told Shots. He's a leading AIDS expert at the University of British Columbia who wasn't involved in the new studies. "We have confirmed that anti-retroviral therapy in non-infected people can protect them against HIV infection."
Now a big question looms: Who should be offered the prevention pill? In some countries candidates would seem to be virtually the entire sexually active population.
Don't look for an answer soon. None of the excited researchers has one. But they all say that it's a good problem to have — a vast improvement over all those years when AIDS prevention boiled down to two inadequate strategies – abstinence and condoms.
"Now we have a nice collection of really powerful strategies that work for the populations that are at greatest risk in the world," says Dr. Jared Baeten of the University of Washington, who led one of the studies. "This is really a game-changer."
The collection now includes these scientifically validated prevention strategies:
- Give the antiviral pills Truvada (a two-drug combination) or Viread to homosexual and bisexual men at high risk of contracting HIV.
- Start anti-HIV therapy as early as possible in infected people, which can nearly eliminate their chances of passing along the virus to others, a strategy called "treatment as prevention."
- Make available a gel containing the antiviral drug tenofavir that women can use before sex to reduce their risk of infection.
- Promote circumcision to reduce HIV infection among men and their sex partners.
During a teleconference Wednesday hosted by the Centers for Disease Control and Prevention, researchers said no more randomized controlled studies are needed to show these methods work. But there will need to be studies to sort out the most effective way to deploy the approaches in different countries and different populations with different HIV rates.
Take the use of a daily prevention pill for uninfected sexually active heterosexuals, the population hardest-hit by HIV globally. "At this point, I don't believe anyone would advocate putting an entire country on anti-retroviral medication," the CDC's Michael Thigpen told Shots. But there are some countries, such as Botswana, where the HIV infection rate is so high that a case could be made for targeting virtually all young adults who aren't infected.
Thigpen, who led one of the new studies — a CDC-sponsored study of 1,200 Botswanian men and women between 18 and 39 — says "up to 50 percent of women in that age group have been infected." The risk of acquiring HIV is 3 percent per year.
Botswana, a small country with more resources than most in sub-Saharan Africa, already has most of its HIV-infected people on treatment who need it. That lessens the competition between giving drugs to people who need treatment and giving the pills to uninfected people to prevent HIV transmission — a debate that can be expected in many countries.
The economics are becoming more favorable to widespread use a prevention pill too. Thigpen says the most recent price he has heard for Truvada in developing nations is 78 cents a pill, or $285 a year. That's a far cry from the $36-a-day or $13,000 price tag in developed countries.
But the price of Truvada might come down even further, some think to as low as 25 cents day or less than $100 a year, under a new agreement by its manufacturer, Gilead Sciences, to license its two active ingredients to an international patent pool that aims to provide cheap drugs to developing countries.
Turning all this into a coherent HIV prevention strategy in country after country, at a time of declining resources, is "going to need more work," says Montaner, the University of British Columbia researcher.
"But in the meantime, this should not be an excuse for policymakers, political leaders and others to say, 'Oh, we need to wait until we solve this problem,' " Montaner says.
"We should not allow that discussion to detract us from what we know we need to be doing – bring treatment to people who are HIV-infected, because it's life-saving, and because it's the most powerful tool we have against transmission" to uninfected partners, he adds.
Montaner points out that a study unveiled this spring showed early treatment of infected people reduced the chance they would pass HIV to others by 96.3 percent. "It's the most powerful tool we have against transmission," he says. "Ninety-six-point-three percent is nothing to laugh about."
He says the Chinese government is moving to expand criteria for HIV treatment "so they can access people earlier, with the ultimate goal of decreasing illness, but also to decrease transmission."