With new infections holding steady in the U.S. at 50-60,000 annually, effective prevention strategies are desperately needed. Increasingly, HIV transmission is being viewed as a problem with a pharmacologic resolution. More clinical data were presented at CROI this year highlighting the role of HAART in halting further transmission, both in individuals and at the community level.
One particularly illustrative cohort was drawn from the Partners in Prevention HSV/HIV Transmission Study which recruited 3408 heterosexual HIV-discordant couples in seven African nations. Previously, this group has reported that herpes prophylaxis with acyclovir to prevent ulcerative disease did not protect individuals with HSV-2 infection from acquiring HIV. This year, Donnell et al. report a more reassuring story regarding HIV transmission.
At the trial’s debut, no HIV-infected participants met national criteria for treatment with HAART. Over the course of observation, 349 HIV-infected individuals reached criteria benchmarks and began HAART. The couples were followed for 24 months during which time uninfected partners were tested for HIV every three months. During this time, 103 linked HIV transmission events were recorded, and all but one of them occurred in couples in which the HIV-infected partner was not taking HAART. In the one exception, a linked transmission occurred just 18 days after the HIV-infected partner had initiated HAART.
The Zurich Primary HIV Infection (ZPHI) study has assessed transmission dynamics in 111 individuals participating in the Swiss HIV Cohort Study. Patients enrolled in ZPHI are treated with “early HAART” right after infection is established. Participants are treated for one year and then offered the option to continue or stop HAART. According to Dr. Philip Rieder, principle author of the study, most opt to stop treatment. Using phylogenetic studies, investigators have linked seven transmission events involving participants of the ZPHI (donors) and the Swiss HIV Cohort Study (seroconverters). Five of the seven transmissions occurred after participants had transitioned off HAART and had detectable viral loads. One transmission occurred before the acutely infected individual had started HAART and one other occurred very soon after HAART was begun. The viral load measurements of the donor patients ranged from 314 to 1.7 million copies HIV RNA/mL. It is surprising and sobering that someone with a viral load as low as 314 would transmit HIV. On the strength of their data, the authors argue that early, continuous HAART in sexually active HIV-positive individuals would be beneficial for the community.
References:
Donnell D, Kiarie J, Thomas K et al. ART and risk of heterosexual HIV-1 transmission in HIV-1discordant African couples: a multinational prospective study. Abstract 136. Seventeenth CROI, San Francisco, 2010.
Rieder P, Joos B, von Wyl V et al. Strong effect of early ART during primary HIV-1 infection in preventing further spread of HIV in sexually active men having sex with men. Abstract 476. Seventeenth CROI, San Francisco, 2010.
02/19/10
PRN Report from 17th CROI: HAART as Prevention
Source: Reporting from San Francisco for PRN News: Kevin Armington, MD