HIV PrEP Can Work in High-Risk Individuals

Benjamin Young, MD, PhD


August 15, 2013

In a previous column I summarized how antiretroviral therapy (ART) can prevent HIV-related illness and prevent new HIV infection. The question is how best to put this knowledge into practice.

Pre-exposure prophylaxis (PrEP) has been shown to be effective in preventing new HIV infections in heterosexuals and in men who have sex with men (MSM),[1,2] and the US Centers for Disease Control and Prevention issued interim guidance on use of tenofovir/emtricitabine PrEP for MSM and heterosexually active adults.[3,4]

PrEP science and policy are moving rapidly. This summer, investigators from the Bangkok Tenofovir PrEP study[5] reported a nearly 50% reduction in incident HIV cases in a randomized study of more than 2400 injection-drug users (IDUs). The authors concluded that tenofovir PrEP can be considered for HIV prevention among IDUs.

Based in part on the results of this Thai study, updated interim guidance for use of tenofovir/emtricitabine PrEP in IDUs was released,[6] noting that "Providing PrEP to IDUs at very high risk for HIV acquisition could contribute to the reduction of HIV incidence in the United States." A comprehensive US Public Health Service guideline on the use of PrEP across different populations is expected later this year.

Yet, HIV prevention strategies can't work unless at-risk populations are aware of effective interventions. In the current issue of the Journal of the International Association of Providers of AIDS Care, Sineath and colleagues[7] from Emory University in Atlanta and the Thailand Ministry of Public Health report on important informational gaps in community knowledge of PrEP. Using Facebook to recruit a very large online survey of over 400 HIV-negative Thai MSM, the study found that fewer than 7% (yes, 7%) had even heard of PrEP.

After survey participants were shown a brief paragraph describing the attributes of PrEP (including statements about effectiveness, requirements for adherence, monitoring tests, and risks for side effects and toxicity), more than one third expressed interest in using PrEP. Many of those who reported a lack of interest said that they would have interest if they started having unprotected sex or if more research showed effectiveness. The survey also asked respondents how much they would be willing to pay for PrEP and found that willingness to use PrEP was very dependent on low cost (< US$25 per month).

The Sineath study is one of a growing set of analyses from around the world, including Canada,[8] China,[9,10] France,[11] Scotland,[12] and the United States,[13,14] that show low awareness but high willingness to use PrEP among at-risk groups. Much like the oft-discussed treatment cascades for HIV treatment,[15] implementation of programs for HIV prevention appears to be vulnerable to many of the same challenges of identifying at-risk populations and bringing these individuals into and retaining them in medical care.