PrEP HIV vaccine may be effective for HIV prevention with intermittent use

A clinical trial in Uganda studying the possibility of using intermittent treatment to prevent HIV in serodiscordant couples via the pre-exposure prophylaxis Truvada vaccine recently reported promising preliminary data.

The study was intended to help serodiscordant couples, couples in which only one of the partners is HIV-positive, make HIV prevention easier by using a vaccine that does not need to be administered daily. The findings of the study, which was conducted by researchers from the Medical Research Council/Uganda Virus Institute's Uganda Research Unit on AIDS in Entebbe, Uganda, were published in the PLOS ONE journal in September.

"PrEP is one of several preventive options helping to stem the tide of HIV, but we don't know enough about whether daily dosing will be achievable in various populations," Chief Medical Officer and Executive Director for Medical Affairs at the International AIDS Vaccine Initiative Frances Priddy said. "This study suggests that an intermittent dosing regimen can be acceptable and have high adherence."

The study looked at 72 HIV-negative volunteers, 36 male and 36 female, and their HIV-positive partners. The volunteers were asked to take either a Truvada pill or a placebo. The dose was either taken daily or intermittently on Mondays and Fridays within two hours of having sex; doses were not to exceed one per day.

Both doses were shown to be well-tolerated, with no adverse effects. Volunteers abided by the study regulations more than 90 percent of the time in both daily and intermittent dosage groups. There was no difference in health found between the groups, possibly indicating that PrEP meds can be used intermittently and still be effective, but more research is required.

"This data adds to our existing knowledge about the use of PrEP for HIV prevention, specifically among HIV discordant couples in Africa," study co-author and MRC/UVRI researcher Anatoli Kamali said. "Given the cost, accessibility and adherence concerns associated with PrEP administered on a daily basis, intermittent PrEP regimens could be a desirable alternative but more research is needed to evaluate efficacy of these regimens."