An insertable ring that slowly releases an HIV-fighting drug can cut in half the risk a woman will get infected — if the woman uses it, researchers reported Monday.
The results are mixed news for efforts to provide women with a discreet way to protect themselves against the fatal and incurable virus. They show that a product can safely work, but they raise the question of whether people can or will use the product correctly.
"This is the first demonstration of a sustained-release approach for HIV prevention," Dr. Jared Baeten of the University of Washington, who led one of two studies on the ring, told reporters.
The vaginal ring reduced the risk of HIV infection by 27 percent on average in more than 2,600 women Baeten's team studied in four hard-hit African countries. But it lowered the risk of infection by 61 percent among women aged 25 and older, the team said in a report published in the New England Journal of Medicine and that will be presented at the Conference on Retroviruses and Opportunistic Infections in Boston.
While a 27 percent rate of protection may seem low, Annalene Nel of the International Partnership for Microbicides, which makes the rings and which ran a second, similar trial, says that can add up quickly in some African communities where 80 percent of adults end up infected.
"If we don't change the current prevention paradigm ... more than half the women in the communities where the study took place would likely become HIV infected over the next decade," Nel told a news conference.
More study showed that the youngest women in the study hardly used the ring at all. They had very little of the drug, dapirivine, in their systems and study of the rings themselves showed most of the drug remained in the plastic.
The older a woman was, the more likely she was to use the ring as intended.
In Nel's study, the ring only reduced the risk of catching HIV by 15 percent in the women aged 18 to 21. In Baeten's study, the protection rate was only 10 percent in women under 25.
The rings are meant to be inserted once a month and then left in place, essentially forgotten, and so the researchers are struggling to figure out why the younger women apparently took them out.
"The advantage to a ring is it can just stay there and you don't have to think about it," said Bethany Young Holt, executive director for the Initiative for Multipurpose Prevention Technologies at the Public Health Institute, who was not involved in either study.
"For some women, their partners can feel it." Those women may have removed the rings, Holt said.
Experts agree that women desperately need something better than condoms to protect themselves from HIV. More than half the 35 million people infected with HIV globally are women, and many live in communities where they cannot refuse to have sex with men, even their husbands.
More than a quarter of new infections in the United States every year are in women, and of the 1.1 million Americans with the AIDS virus, 280,000 are women, according to the Centers for Disease Control and Prevention. Black women are especially vulnerable - their infection rate is 15 times the infection rate for white American women.
"Women need a discreet, long-acting form of HIV prevention that they control and want to use," said Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, which helped pay for the study.
For more than two decades researchers have been testing gels, creams, films and other products that women, and men, too, could use to protect themselves from the sexually transmitted virus.
Once-a-day pills used in an approach called pre-exposure prophylaxis or PrEP can reduce the risk of catching HIV by 90 percent if people use it consistently. It's been on the market since 2012 and has been recommended by the CDC since 2014. But it's not cheap and studies suggest it could be difficult for young African women to stick to.
Baeten pointed out that in early studies of PrEP, it wasn't as effective as real-life studies show it is. It could be that women did not use the vaginal ring consistently because they knew they were volunteering in an experiment. They did not know if the ring was safe or if it even protected them from HIV.
Now that the trials show the ring is safe - there were very few side-effects - and can work if used correctly, women may be more likely to use it and stick with it, he said.
Holt said women also need a variety of options.
"What we hear is that at different times of a woman's life, she is going to need a different type of product," Holt said.
"At some times in women's lives, they are going to want something that is quick and spontaneous. When a woman is married, she may need something that is long-acting."
Holt, who studies and advocates for the use of multi-purpose technologies, which can protect women against pregnancy, HIV and other sexually transmitted infections at the same time, said adding a birth control element might also make a woman more likely to use a product consistently.
"IPM has a version of this ring that is combined with levonogestrol, with a hormone," Holt said. "That could be so empowering for women, to have something that can prevent pregnancy and HIV."
It might be more socially acceptable, as well, Holt said, for a young woman to say a product she is using is meant to protect her against pregnancy.