Questions on Tactic to Prevent H.I.V.

Published: October 10, 2011

In the past year, three landmark clinical trials have shown that a daily dose of the antiretroviral medication Truvada can protect individuals from infection with H.I.V. — a significant discovery, given the failure so far of all efforts to develop a vaccine against the virus.

Now researchers in San Francisco and Miami are planning to test this prevention strategy, called pre-exposure prophylaxis, or PrEP, in a pilot study supported by the National Institutes of Health. The researchers will soon recruit up to 500 uninfected men who have sex with men, especially those considered to be at greatest risk of infection, such as younger gay men and, in particular, African-Americans.

The men will be asked to take Truvada daily, and the researchers will monitor their compliance with the regimen, their sexual behavior and their health status. Already, though, the prospect of antiretroviral drugs’ being used for prevention as well as treatment is raising complex questions for researchers and advocates.

Will healthy uninfected people consistently take an expensive and powerful drug that can cause a range of side effects? Is it fair to provide medications to H.I.V.-negative individuals when so many of those already infected do not have access? Will those receiving the drug be more likely to engage in risky sex because they believe they are protected — even if they do not always take it as prescribed?

The issues are more than academic: According to anecdotal reports, some doctors are already prescribing the medications to some H.I.V.-negative patients, said Dr. Kenneth Mayer, a chairman of the Fenway Institute, a research and advocacy center for  gay, lesbian, bisexual and transgender health in Boston, who has been involved in research into PrEP.

“I think that’s going to increase, but it’s very incremental,” said Dr. Mayer, who believes PrEP is an important new weapon in the H.I.V. prevention arsenal. “People have a lot of questions.”

AIDS advocates have generally expressed optimism that the strategy, if applied carefully, could help reduce the approximately 50,000 new H.I.V. infections that occur annually in the United States. But one major provider of services to people with H.I.V., the AIDS Healthcare Foundation in Los Angeles, has initiated a media and ad campaign raising serious concerns.

The foundation’s president, Michael Weinstein, noted that participants in the first round of PrEP research were counseled extensively that not following the protocol could reduce any protective effect, and yet many still failed to take their pills as prescribed. Adherence to the regimen is likely to be even worse under real-world conditions, he said.

“We deal with tens of thousands of patients here who are positive, and a high percentage of them have adherence issues,” said Mr. Weinstein. “So the idea that young gay men who don’t have this disease are going to take this routinely is highly questionable.”

Mr. Weinstein is particularly concerned that the Food and Drug Administration could soon approve Truvada for use in H.I.V. prevention as well as treatment, which would undoubtedly lead to greater use of the drug. Gilead Sciences, the company that makes the drug, has said it is likely to file such an application with the F.D.A. early next year.

Once the F.D.A. approves a drug for any use, doctors can legally prescribe it “off-label” for other purposes. Drug companies, however, are allowed to promote their products only for indications specifically approved by the agency.

In one of the three earlier clinical trials, among men who have sex with men, PrEP reduced new infections by 44 percent over all. Among men who adhered closely to the prescribed daily regimen, however, protection against infection was greater than 90 percent.

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