A vaginal ring containing an antiretroviral (ARV) drug called dapivirine could help women protect themselves against HIV if rolled out.
The results came from a large-scale clinical trial involving more than 2,600 women in Africa with researchers who conducted the trial, known as ASPIRE, reporting that the dapivirine ring reduced the risk of HIV infection by 27 percent overall.
The study, which was led by the National Institutes of Health (NIH)-funded Microbicide Trials Network (MTN), found that there were 27 percent fewer women who acquired HIV in the group assigned to use the dapivirine ring than in the group assigned to use a placebo ring containing no active drug.
The risk of HIV was reduced significantly more among the study’s older participants, who also used the ring most consistently. Women in the dapivirine group who were 25 and older were 61 percent less likely to acquire HIV than women of the same age in the placebo group.
Due to the finding, the researchers conducted additional analyses which drew a more precise line of demarcation, with lack of protection being confined to women between the age of 18 and 21, and women older than 21 seeing their risk of HIV cut by more than half (56 percent).
ASPIRE enrolled HIV-negative women ages 18 to 45 at 15 clinical research sites in Malawi, South Africa, Uganda and Zimbabwe.
Results of the ASPIRE study were announced at the Conference on Retroviruses and Opportunistic Infections (CROI) in Boston on Monday.
In the second trial, called The Ring Study, HIV risk was reduced by 31 percent overall, and by 37 percent among participants older than 21. The International Partnership for Microbicides (IPM), which developed the monthly dapivirine ring, is conducting The Ring Study in South Africa and Uganda among 1,959 women.
Although still ongoing, The Ring Study is reporting results early, following a recommendation of its independent data and safety monitoring board that the study proceed to final analysis.
“This is a glass-half-full moment,” said Jared Baeten, M.D., Ph.D., of the University of Washington, who as protocol chair led the ASPIRE study.
“The HIV prevention field for women has struggled in the last few years – at times the glass had seemed almost completely empty. Now, for the first time, we have two trials demonstrating that a female-controlled HIV prevention method can safely help reduce new HIV infections. I’m optimistic about what these results might mean for women worldwide.”
Women account for nearly 60 percent of adults with HIV in sub-Saharan Africa, where unprotected heterosexual sex is the primary driver of the epidemic.
While several studies have shown that ARVs are highly effective in preventing HIV, other studies – such as VOICE and FACTS 001 – suggest that for young, at-risk women in Africa, ARVs delivered as a vaginal gel or as a tablet may not be acceptable. Products must be used to be effective, and that was not the case for most of the participants in those previous studies.