Surprisingly, study participants who used the new oral method, called pre-exposure prophylaxis -- or PrEP -- reported a higher compliance with other HIV prevention methods such as condom use, and also reported a decrease in the number of sexual partners, said Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, an arm of the National Institutes of Health in Bethesda, Md., which partly funded the study.
While preventive antiretroviral therapy is an innovative method, it's likely to be only part of the larger HIV prevention effort, he said.
All study participants received additional HIV prevention, including condoms, counseling, as well as periodic HIV testing. However, the rise in HIV infections is attributed in large part to the failure of high-risk groups to use prevention methods.
Dr. Robert Grant, a study chairman at Gladstone Institute of Virology and Immunology at the University of California at San Francisco, warned self-reported use of medication often proves to be higher than actual use.
Grant said one of the challenges of Truvada may be that some may find it difficult to take the pill daily.
"Finding ways to support use of daily pill is the focus of the next studies," said Grant, adding that future studies should determine whether more limited and shorter term use of the pill, along with other available prevention methods, may prove just as effective.
"Sustainability of treatment programs requires that something needs to be done to decrease infection [rates]," Grant said.
Truvada is commonly used as a therapy for patients already infected with HIV. In most countries, the pill costs about 40 cents a day, Grant said. However, Grant also said it's likely the price of the drug would rise if used as a prevention method.
Regardless of the FEM-PrEP study halting, two additional studies of Truvada are currently enrolling women in Africa.
"It's important that efforts to find an additional HIV prevention tool continue," said Mastro.