The ring contains an antiretroviral medication called dapivirine, which prevents HIV from making copies of itself. In the ring, the drug is used as “pre-exposure prophylaxis,” or PrEP, slowly leaching out in the vagina and preventing the virus from taking hold in nearby cells.
Looking by age, the researchers saw that the ring did not seem to help women younger than 21. But among women over the age of 21 who used it, new HIV cases went down by 61%.
The other study, which has not yet been published but was presented on Monday at the Conference on Retroviruses and Opportunistic Infections meeting in Boston, studied 2,000 women in South Africa and Uganda. Like the other study, in this one the ring had no visible effect in women younger than 21, whereas new HIV cases dropped by 37% in women over 21.
The ring adds a new HIV prevention tool, which some experts say will be particularly useful in African countries where women are at highest risk for HIV infection. More than half of the 35 million people living with HIV worldwide are women, and the vast majority live in sub-Saharan Africa.