October 1, 2007

HIV PrEP: Should We or Shouldn’t We?

Here’s Robert M. Grant, MD, MPH, of the Gladstone Institutes in San Francisco, on why HIV prevention strategies so far have failed: Abstinence programs? “My kids say it’s proof of adult stupidity.” Condoms? “Like showering with your socks on.” Male circumcision? Well, he said, considering it involves removing a significant area of the penis, “It’s no wonder that women are more interested in male circumcision than are men.”

The point is, he said, “Prevention concepts have not worked because people don’t use them. They interfere or alter sex in some way that people care about.”

That’s why Dr. Grant backed pre-exposure prophylaxis (PrEP) during the “Clinical Controversies” session at IDSA 2007 this month in San Diego. Antiretroviral drugs work without altering sex, he noted. They’re ready to prescribe now. Grant quoteThey’re already prescribed for post-exposure prophylaxis and against mother-to-child transmission. And they are “at least as female-controlled as a microbicide—and more easily concealed,” he said.

And so far, at least, they appear to work. Tenofovir studies in non-human primates, health care workers following needle sticks, and discordant couples seeking to have children have shown promising results, Dr. Grant said. And in a phase II study in West Africa he co-authored, tenofovir PrEP appeared safe and there is a promising trend toward efficacy, although efficacy has not yet been established.

Wrong Idea, Wrong Time

For the sake of this debate, Willard Cates, MD, of Family Health International and senior author of the West African phase II tenofovir study, set himself up as the “con man”—saying there are biological, behavioral, economic, and societal reasons not to endorse PrEP.

The biological data are weak, he said. Animal models have yielded mixed and uninterpretable results, and human trials have a long way to go. The West African tenofovir study “is somewhat encouraging,” he acknowledged, “but as you all know, we need much more data from thousands of people before we can really give any of these antiretrovirals in uninfected people a clean bill of health.”

“The big threat, of course, is resistance,” he added. In animal models tenofovir-resistant strains developed rapidly, even under high doses. Explosive transmission of resistant HIV during the early, acute phase of infection would be a disaster. “We’re really setting ourselves up for the next Andromeda Strain of HIV,” he said.

Behaviorally, Dr. Cates said PrEP will encourage people to engage in riskier sex and forego proven prevention methods like condoms, circumcision, and limiting sex partners. In the United States, he noted, there are already reports of people at dance clubs using tenofovir before engaging in high-risk sexual activity. Scaling that up to all the beer halls in Africa would create what he called “a continental powder keg.”

Furthermore, he said, PrEP carries costs. Even at deep discounts from the manufacturer, tenofovir PrEP costs $20 a month, well out of reach for people in most developing countries. There are societal costs as well, he added. Consider the societal perceptions of “allowing or even encouraging illicit behaviors by passing out pills to make unsafe sex or drug use even easier,” he said.

“Lastly, the public health impact is, indeed, questionable,” he concluded. Under realistic assumptions, modeling studies show a modest impact at best—and resistance is a big issue.

“PrEP is the wrong idea, at the wrong time,” Dr. Cates “concluded.”

Offstage, however, the two actually agree: It would be a mistake to let fears about possible risks interfere with studies to answer these questions. Nor should ideology get in the way. Let the evidence decide, they say, whether PrEP is the right idea at the right time.

Slides from this session and many others from IDSA 2007 are available online.

Audio files, including a full-conference CD-ROM, are available for purchase from Sound Images.

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Thinking Outside the Box
ART, Circumcision, STI Treatment as HIV Prevention
Global Surveillance, Vaccine Use Key to Controlling Seasonal Influenza
Bad Bugs on the Run
IDSA Advocacy Update
HIV PrEP: Should We or Shouldn’t We?
Keep Up with Drug Approvals, Recalls, Adverse Events
Lyme Disease: When Symptoms Don’t Improve
Alternative Approaches, Possible Vaccines Against MRSA Infections
New Hope for Viral Suppression in All HIV Patients
Resistant Staph: Use One Drug or a Combination?
Congratulations to the 2007 Society Award Recipients
Winners of the 2007 IDSA/SHEA Advancements in MRSA Awards
Congratulations to This Year’s 50 Outstanding Scholars!
IDSA Announces New Board Members
Welcome, New IDSA Members!
Electronic Tools for Infectious Diseases Practitioners
From the President
Public Reporting of HAIs May Have Unintended Consequences
Treatment Options for C. difficile
XDR TB: Where it Came From, Where We’re Going
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