WASHINGTON, D.C. - A new vaginal ring providing sustained release of the antiretroviral (ARV) dapivirine was shown to help reduce the chance of HIV infection during vaginal sex among women ages 18 and older. USAID, through the United States President's Emergency Plan for AIDS Relief, provided $25 million in support for the trial and ring licensure.

Results of the Ring Study, led by the International Partnership for Microbicides (IPM), were announced at the Conference on Retroviruses and Opportunistic Infections today. The study showed that the monthly dapivirine ring safely reduced HIV infection overall by 31 percent compared to a placebo. Similar results were seen in ASPIRE, led by the National Institutes of Health-funded Microbicide Trials Network (MTN), which found that the ring safely reduced infection by 27 percent overall. This is the first time two Phase III studies have confirmed statistically significant efficacy for a microbicide to prevent HIV.

The Ring Study enrolled 1,959 women at seven sites in South Africa and Uganda, and ASPIRE enrolled 2,629 participants at 15 sites in Malawi, South Africa, Uganda and Zimbabwe. ASPIRE began in 2012 and ended in 2015. The Ring Study also began in 2012 and is now reporting results early after a review by its independent data safety and monitoring board recommended the study proceed to final analysis.

HIV protection appeared to increase with age and consistency of ring use. Women over the age of 21 appear to have used the ring more consistently, with efficacy at 37 percent. However, women ages 18-21 showed little to no protection, and work is being done to assess the contributing factors.

"There is a clear need for HIV prevention options for women. These results show promise, and while more research is needed, we look forward to further exploring how the dapivirine ring can help protect women," said USAID Assistant Administrator Ariel Pablos-Méndez.

In some parts of Africa, young women are more than four times as likely to become infected as young men. Even with marked improvements in HIV treatment, women continue to be at disproportionately high risk of infection, especially in Africa where HIV/AIDS is the leading cause of death worldwide for women of reproductive age.

"In 2016, all AIDS-related deaths are preventable deaths, and we must empower women across the world to help protect themselves from HIV," added Pablos-Méndez.

Based on today's results, IPM is planning an open label extension study that would provide previous Ring Study participants with the dapivirine ring, and help answer critical questions about the product and its use while it is under regulatory review for licensure. As part of its commitment to support the development of additional prevention options that women can use to protect themselves from HIV infection, USAID will continue to invest in new products such as the IPM dapivirine-releasing vaginal ring. This will include support for the protocol amendment recently approved by the Medicines Control Committee of South Africa for the Ring Study that will make the active dapivirine-releasing rings available to those participants who have been receiving placebo rings.

In addition to USAID through PEPFAR, IPM's work is made possible through generous support from the Ministry of Foreign Affairs of Denmark, Flanders Department of Foreign Affairs, Irish Aid, the Ministry of Foreign Affairs of the Netherlands, the Norwegian Agency for Development Cooperation (Norad), the United Kingdom Department for International Development (DFID), and the Bill and Melinda Gates Foundation.