NIH studies find success blocking HIV transmission with vaginal ring, drug regimen

Findings announced by the National Institutes of Health (NIH) could lead to new methods of reducing the risk HIV transmission through breastfeeding and sexual intercourse.

In the latter case, the decreased infection risk could be achieved through women using a vaginal ring that continuously releases dapivirine. According to NIH, an analysis of data from its ASPIRE study found women who use the ring most or all of the time reduced their risk of HIV infection by 56 percent.

“The findings from the ASPIRE study told us how much protection the dapivirine ring afforded the study population as a whole, which included women who used the ring often, sometimes or not at all,” said Anthony Fauci, MD, director of the National Institute of Allergy and Infectious Diseases (NIAID). “However, we know that HIV prevention tools work only if people use them. The findings of the exploratory analysis reported today give credence to the hypothesis that greater adherence to the dapivirine ring translates into a higher level of protection.”

NIAID is funding a follow-up clinical trial that will further determine the relationship between the ring's use and protection from HIV, along with evaluating the safety of the ring’s long-term use.

The other study found greater success in preventing a HIV-positive mother from transmitting the virus to her child through breast milk.

The large clinical trial, involving more than 2,300 HIV-positive mothers and their uninfected infants in several African nations and India, found that using a three-drug antiretroviral therapy, as well as infant nevirapine, virtually eliminated all risk of HIV transmission to the child.

“The rate of perinatal transmission did not differ between the two study arms and was very low — 0.3 percent at 6 months of age and 0.6 percent at 1 year of age,” the study said. “The longer an HIV-infected mother breastfeeds, the greater the risk for HIV transmission to the infant. In comparison, in the absence of any intervention, rates of HIV transmission from a HIV-infected mother to her child during either pregnancy, labor, delivery or breastfeeding historically have ranged from 15 to 45 percent.”

Infant mortality was very low among the study participants, with 99 percent of the children living to their first birthday.

The results of both studies were announced at the 21st International AIDS Conference being held in Durban, South Africa.