We Can (Kinda) Prevent Drug Users from Getting HIV

A once-a-day antiretroviral pill can cut HIV transmission in drug users by up to 70 percent, according to a major new study.

The drug, Tenofovir, is already in common use as a HIV treatment and was approved by the Food and Drug Administration in 2006. But a recently-wrapped, eight-year clinical trial in Bangkok, published in Lancet, found that intravenous drug users who took Tenofovir daily were 75 percent less likely to contract the virus than those who took a placebo. Overall, the drug lowered HIV infection rates by about 50 percent if not taken every day.

Researchers call it pre-exposure prophylaxis (PrEP), and other than completely abstaning from shooting up it represents one of our best chances of fighting transmission of the disease.

“This is a significant step forward for HIV prevention. We now know that PrEP can work for all populations at increased risk for HIV,” said Jonathan Mermin, the Centers for Disease Control's director of HIV / AIDS Prevention. “Injection drug use accounts for a substantial portion of the HIV epidemic around the world, and we are hopeful that PrEP can play a role in reducing the continued toll of HIV infection in this population.”

Previous studies have demonstrated that Tenofovir can be effective in reducing the risk of sexual HIV transmission. It's also been shown to reduce transmission by about 44 percent in gay men and by nearly two thirds in straight men and in women. The latest findings are the first to suggest that protection extends to drug users. Mermin said that the CDC will publish guidelines today asking doctors to prescribe PrEP to drug users at their discretion.

In most of the world, sexual transmission of HIV is of greatest concern. But in some areas such as eastern Europe and much of Asia, as much as 80 percent of all HIV infections are caused by infected needles. In Thailand, roughly half of intravenous drug users have HIV.

Tenofovir doesn't provide complete protection against infection--of the study's 1,200 participants, 17 still contracted HIV. But at least it's something. The CDC suggests, obviously, that "the best way for people who inject drugs to reduce their risk for HIV is to stop using injection drugs." But Tenofovir, combined with syringe exchange programs is our next best bet.

That's the new reality in the fight against the disease. We still seem pretty far away from a true cure, and we still can't completely prevent infection. And yet we're getting reasonably good at fighting it off for a while and cutting transmission. In pregnant women, for instance, antiretroviral therapy cuts the transmission rate to infants to below 1 percent.

It's been an exciting couple weeks for HIV research: Late last month, researchers used a supercomputer to find a weakness in HIV's protein coating, and a recent National Institutes of Health study found the exact method that HIV kills immune system cells.

Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, said that until researchers can selectively target the cells where HIV lies dormant in the body, a true cure is unlikely, and reducing transmission rates remains our best shot.