anti-HIV ring
File photo: Wits Reproductive Health and HIV Institute (WRHI) in Johannesburg shows a Dapivirine vaginal ring to be used in an HIV prevention trial in 2012 Getty

Scientists have come up with a new tool to protect women from human immunodeficiency virus (HIV) infections – a silicone vaginal ring which releases an experimental antiretroviral (ARV) drug. Research was conducted to establish whether ARV dapivirine could safely prevent HIV infection when continuously released in the vagina.

The Aspire study followed 2,600 uninfected women at high risk of contracting HIV. The sample included women aged between 18- and 45-years-old from Malawi, Zimbabwe, South Africa and Uganda. At the end of the study, scientists were provided with modest evidence that the silicone ring releasing dapivirine has a positive, protective effect on women.

Dapivirine vs placebo

The women were divided into two groups and asked to wear a silicone vaginal ring that was changed every four weeks. In the placebo-controlled double-blind test, half of the group were given a ring which released dapivirine, while the others were assigned a placebo ring.

Throughout the trial, all participants were closely monitored by healthcare workers, with a great focus on prevention. At each study visit they were offered HIV risk-reduction counselling and free condoms. Their partners were tested for HIV, and both were treated for any sexually transmitted diseases.

According to their findings, published in the New England Journal of Medicine, the ring reduced the risk of acquiring HIV by 27%. Once the researchers excluded from the data the women who did not return for follow-up visits or who used the ring consistently, this figure rose to 37%.

Age makes a difference

In Sub-Saharan Africa, more than 25 million people still live with HIV, half of them women. 48% of the world's new HIV infections among adults occur in the region.

Teen girls and young women are particularly affected, with one quarter of new infections happening amongst them. To help them, scientists are trying to come up with alternative methods to prevent new infections, the vaginal ring being one of them.

The study results varied greatly depending on the women's age. The risk of HIV infection was reduced by 61% in those older than 25 but it did not have any statistically significant impact on their younger peers.

Further research is needed to understand that result, but the scientists believe the younger group used the ring less consistently than the older women, based on the generally lower level of dapivirine in their blood.

"The Aspire study is the first to demonstrate that a sustained drug delivery product that slowly releases an ARV drug over time can offer partial protection from HIV," explained Thesla Palanee-Phillips, co-author of the study.

Co-author Jared Baeten said: "To help bring about an end to the HIV/AIDS epidemic, women need multiple options for HIV prevention. The Aspire study was an important step towards determining whether the dapivirine ring could become one such option."

Another study, The Ring, financed by the Bill and Melinda Gates Foundation came up with similar findings. Scientists also tested the dapivirine ring for safety and efficacy in women. There, they found a 31% reduction in risk of HIV, with slightly better results for women older than 21 years.

"Women urgently need better options for HIV prevention, especially options that allow them greater control," said Luiz Loures, deputy executive director of UNAIDS. "The path to an effective microbicide has been a long one. The important results from these two studies take us one step closer towards an HIV prevention product that could protect millions of women worldwide."