A monthly vaginal ring that contains an anti-retroviral drug has been shown to cut the risk of HIV infection in women by nearly one-third, according to two international studies.
The results, announced on Monday at the Conference on Retroviruses and Opportunistic Infections in Boston, US, revealed that the vaginal ring prevented about a third of HIV infections among the women who used it in the research.
The dapivirine ring was even more effective in women over 25, who saw their risk of HIV drop 61 percent while using the ring.
The study asked volunteers to insert a ring that slowly releases dapivirine into the vagina and its walls to prevent HIV in case of unprotected sex with a man who is HIV positive. The dapivirine ring reduced the risk of HIV infection by 27% overall.
The research also adds a new dimension to preventing HIV infection by encouraging healthy people to take anti-retroviral drugs, a strategy known as PrEP, or pre-exposure prophylaxis.
Previous trials using another anti-retroviral drug — tenofovir — in pill form and as a vaginal gel have not been shown effective in African women.
Both studies found large differences in how effective the ring was at preventing HIV according to the age of the women using it.
According to the IPM statement, “little to no protection was seen in women ages 18-21 across both studies — 15 percent in The Ring Study and no protection in ASPIRE.”
But women over 21, who appeared to use the ring more consistently, saw their risk of HIV drop by 56 percent in the ASPIRE study.
Scientists at the CROI said that more research was needed so as to understand what factors could have led to the difference in outcomes.
“These findings give new hope to many women at high risk who need more and different options to effectively protect themselves from HIV,” said Zeda Rosenberg, founding chief executive officer of IPM.
The dapivirine ring, which women insert and leave in place for one month, is the first long-acting ARV-based product to be tested for efficacy.