(CN) - A vaginal ring has been shown to reduce the risk of HIV infection among African women, according to the National Institutes of Health.
Women in four sub-Saharan African countries used the ring, which releases an experimental, antiretroviral drug called dapivirine in the vagina.
Use of the ring lowered the risk of HIV infection by 27 percent, according to the National Institute of Allergy and Infectious Diseases (NAIAD).
That number jumped to 61 percent among women ages 25 and older, who were most likely to use the ring consistently.
"Women need a discreet, long-acting form of HIV prevention that they control and want to use," said Dr. Anthony Fauci, the director of the NAIAD, which is part of the National Institutes of Health (NIH).
Fauci added that further research would help to understand the age-related differences in the study results.
The ASPIRE study - the results of which were announced Monday - followed 2,600 women in South Africa, Uganda, Malawi and Zimbabwe. The ring continuously released the drug and was replaced every four weeks.
Almost 26 million people lived with HIV in sub-Saharan Africa in 2014. More than half of those patients were women. One of every four new HIV cases in the region is an adolescent girl or a young woman, according to the NIH.
The New England Journal of Medicine published the study results online as they were announced in Boston at the Conference on Retroviruses and Opportunistic Infections.
"The ASPIRE study is the first to demonstrate that a sustained drug delivery product that slowly releases an antiretroviral drug over time can offer partial protection from HIV," Dr. Thesla Palanee-Phillips, one of the study's co-leaders, said in a statement.
Results from another multinational dapivirine trial called The Ring Study showed a 31 percent effectiveness rate. That study was also presented at the research conference.
NAIAD was the main funding source for the ASPIRE study.
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