New interim study results show women are open to using a vaginal ring for HIV prevention, but scientists are still trying to figure out when it works, and why.
Jared Baeten, MD, PhD
Preliminary findings from a new open-label study of a vaginal ring infused with an anti-HIV drug show the vast majority of women use the device at least once, though plenty of questions remain about just how effective a tool the device will be, and for whom.
The data come from the HIV Open-Label Extension (HOPE) Study, which is a follow-up to the ASPIRE HIV-Prevention Study, and the results of which were published in 2016.
Lead author Jared Baeten, MD, PhD, professor of global health, medicine and epidemiology at the University of Washington, in Seattle, said the ring could be an important part of the HIV-prevention equation because it would give women additional power when it comes to preventing HIV transmission.
“Women account for the majority of new HIV infections worldwide,” he told MD Magazine. “For many women at risk for HIV, HIV prevention strategies — like condoms or HIV treatment – are in the hands of her partner. Methods like the dapivirine vaginal ring get HIV prevention under her control.”
The HOPE Study is being carried out in Malawi, South Africa, Uganda, and Zimbabwe. More than 1400 sexually-active women ages 20—49 are participating in the study. Each woman is given a vaginal ring that continually releases the drug dapivirine. The rings can be inserted into the vagina for up to 1 month. Initially, patients are given 1-month supplies at each visit, but after 3 months they are allowed to scale back to quarterly clinic visits, receiving 3 rings at each visit.
More than 90% of women accepted the ring when offered. Of those, 89% returned rings showing residue of dapivirine, suggesting most women used the ring at least once. That’s higher than the 77% usage rate reported in the ASPIRE trial.
However, the uptake numbers only tell part of the story. That’s because the ring’s actual efficacy is impacted by a number of factors, some of which are more difficult to quantify, said Carl W.
Dieffenbach, PhD, director of the Division of AIDS at the National Institute of Allergy and Infectious Diseases (NIAID) at the National Institutes of Health.
In the ASPIRE Study, for instance, the vaginal ring decreased the risk of HIV infection by 27%. However, Dieffenbach said that number might be heavily influenced by patient adherence rates. It’s not yet clear how effective the ring would be with perfect adherence.
“That is really the $64,000 question,” he said.
Furthermore, the ring is designed for one specific purpose — to prevent HIV transmission during vaginal sex.
Carl W. Dieffenbach, PhD
“You’re protecting women who practice sex in only one way,” he said.
Notably, the ASPIRE study found a very significant age disparity with regard to the vaginal ring’s protection levels. In women ages 25 and older, the ring reduced HIV infection risk by 61%. But in women under 25, there was no statistically significant reduction in risk. That gap was partly attributed to less consistent use by younger patients. However, it could also be affected by other differences in sexual habits among the different age groups, from rates of condom and pre-exposure prophylaxis usage, to types of sexual behavior. Anal sex, for example, carries a higher risk of HIV transmission than vaginal sex, according to the US Centers for Disease Control and Prevention.
“The issue as we go forward is that we need to think about who will be using these products and are they right for everybody?” Dieffenbach said.
If the ring is approved and put into broad use, scientists will have plenty of real-world data from which to draw more precise conclusions about the ring’s role in global HIV prevention.
However, Dieffenbach said until those questions are answered, regulators are in a difficult spot, facing questions of whether to recommend something that is still surrounded by so many question marks.
“How do you deal with that in an ethical way?” he said. “That’s the struggle that the regulators and others are going to have as they go forward to look at this ring.”
The interim results were presented earlier this month at the Conference on Retroviruses and Opportunistic Infections (CROI), in Boston.
The HOPE Study is part of the NIH-funded Microbicide Trials Network. The study is sponsored by the International Partnership for Microbicides (IPM), which developed the ring.
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