HIV virons (green) budding from a white cell -- Photo: C. Goldsmith/CDC

One pill a day can slash risk of HIV infection, UW study finds

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HIV virons (green) budding from a white cell -- Photo: C. Goldsmith/CDC

One pill a day can more than halve the risk that an uninfected partner in a heterosexual relationship will contract HIV from an infected sexual partner, a University of Washington study has found.

Such couples are called “serodisordant” because blood tests, called serological tests, indicate that one is infected with the virus that causes AIDS, HIV, and the other is not.

The study’s findings are “clear evidence that this new HIV prevention strategy, called pre-exposure prophylaxis (or PrEP), substantially reduces HIV infection risk,” the researchers said in a statement announcing the results.

“This study demonstrates that antiretrovirals are a highly potent and fundamental cornerstone for HIV prevention and should become an integral part of global efforts for HIV prevention,” said said Dr. Connie Celum, a UW professor of global health and medicine and the principal investigator of the study, known as the Partners PrEP Study.

The study was conducted by the UW International Research Center and  funded by the Bill & Melinda Gates Foundation.

The study, which is continuing, involves 4,758 HIV serodiscordant couples, in which one partner has HIV and the other does not, from nine research sites in Kenya and Uganda.

In the study, partners who were not infected with HIV took a daily tablet containing an HIV medication – either the antiretroviral medication tenofovir, tenofovir in combination with another antiretroviral emtricitabine, or a placebo.

A review by the study’s research team and the study’s Data and Safety Monitoring Board (DSMB), an independent group of experts that monitored the study’s conduct and safety, concluded over the weekend that the evidence of the drugs’ protective effect was so strong that the study results should be made public early and the placebo arm of the study be discontinued.

The board also recommended that the study continue with those receiving tenofovir and tenofovir combined with emtricitabine remaining on those medications and those receiving placebo to start receiving the drugs.

The review found that a total of 78 HIV infections occurred in the study: 18 among those in the tenofovir group, 13 among the drug combination group, and 47 among those assigned placebo.

Statistically, this means those taking tenofovir had an average of 62 percent fewer HIV infections and those who took the drug combination had 73 percent fewer HIV infections than those who received placebo.

“This is an extremely exciting finding for the field of HIV prevention,” said Dr. Jared Baeten, co-chair of the study and a UW associate professor of global health and medicine. “Now, more than ever, the priority for HIV prevention research must be on how to deliver successful prevention strategies, like PrEP, to populations in greatest need.”

To learn more:

  • Visit the UW International Research Center’s Partners PrEP Study webpage.
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