PrEP Could Prevent Three Million HIV CasesIin Sub-Saharan Africa

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Pre-exposure prophylaxis -- the practice of HIV-negative people takingantiretroviral drugs before potential exposure to the virus -- couldprevent as many as three million new HIV cases over 10 years insub-Saharan Africa, according to a study published online Wednesday in PLoS One, Reuters reports (Fox, Reuters, 9/18).

For the study, researchers at the University of Pittsburgh School of Medicine and Imperial College London used a computer model to predict by how much Gilead Sciences'antiretroviral tenofovir, sold under the brand-name Viread, couldreduce new HIV cases. In studies involving monkeys, tenofovir has beenshown to be effective in preventing transmission of the simian versionof HIV, AFP/Yahoo! News reports (AFP/Yahoo! News, 9/18). According to Reuters, the model simulated an African country where 20% of the adult population is living with HIV/AIDS (Reuters, 9/18).

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Theresearchers found that if the drug was effective 90% of the time andwas given daily to 75% of sexually active people ages 15 to 49, itcould reduce HIV cases by 74% over 10 years (AFP/Yahoo! News, 9/18). The researchers estimated that such a program would cost about $2 billion over 10 years in Southern Africa (Reuters,9/18). If the drug was effective 60% of the time and was taken by 50%of sexually active people ages 15 to 49, it would reduce HIV cases byabout 25% over 10 years, according to the researchers. In addition, ifthe drug was effective 30% of the time and used by 25% of sexuallyactive people, it would reduce new cases by 3.3% over 10 years, thestudy found (AFP/Yahoo! News, 9/18).

According tothe study, about 2.7 million to 3.2 million new HIV-1 cases could beprevented over 10 years in sub-Saharan Africa by providing PrEP topopulations with high sexual activity. John Mellors, a professor at theSchool of Medicine who helped direct the study, added that PrEPprograms should include counseling to determine who should take thetreatment and ensure that people do not have a false sense ofinvulnerability to HIV. "If the public feels that they can take a pilland now have more sex, the effect of the PrEP will go way down,"Mellors said.

According to Mellors, the researchers looked atthe efficacy of PrEP, how quickly the target population begins therapyand whether they continue therapy, and what population should betargeted. Mellors said that providing PrEP to the two groups at highestrisk for HIV, or about 18% of the population, would be the mostcost-effective approach (Reuters, 9/18). Ume Abbas, anassistant professor at the School of Medicine and lead study author,added that even if PrEP with tenofovir is found to be effective inhumans, it is "never going to be feasible to treat the entirepopulation."

NIHis funding five separate studies on PrEP with tenofovir to determineits effectiveness among high-risk groups -- such as commercial sexworkers, injection drug users and men who have sex with men -- withresults expected by early 2008, AFP/Yahoo! News reports (AFP/Yahoo! News, 9/18).

Reprinted with permission from kaisernetwork.org. You can view theentire Kaiser DailyHIV/AIDS Report, search the archives, and sign up for email delivery at kaisernetwork.org/email . TheKaiser Daily HIV/AIDS Report is published for kaisernetwork.org, a free service ofThe Henry J. Kaiser Family Foundation.

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