The Dapivirine vaginal ring used in an HIV prevention trials.
A vaginal ring infused with anti-HIV medication can reduce women’s chances of contracting the virus by almost a third – and by up to 56% in women older than 21 – according to the results of two clinical trials announced at the annual Conference on Retroviruses and Opportunistic Infections in Boston in the United States on Tuesday.
The trials required over 4 000 HIV-negative women aged between 18 and 45 in South Africa, Uganda, Zimbabwe and Malawi to insert a flexible silicone ring containing the antiretroviral dapavirine into their vaginas. They had to replace the ring every month over a period of two years.
The two studies – known as the Ring Study and the ASPIRE trial – were started in 2012 and designed in collaboration with the Partnership for Microbicides and the Microbicides Trials Network respectively.
These results are “ground-breaking” as they offer another prevention option to women who often cannot negotiate condom use with male partners, said Jared Baeten, who lead the ASPIRE trial.
“This is the first example of a long-acting prevention method which, as these results tell us, is extremely safe and is also effective,” said Baeten.
“It’s also easy to use: there wasn’t a single case where a woman could not insert the ring or remove it at the end of the month,” he said.
According to Baeton, another advantage is that the ring is discrete with “little to no impact” on sexual pleasure and did not cause discomfort in day-to-day life.
“This is important for women who need to keep their prevention methods a secret from their male partners,” he said.
Annelene Nel, who lead The Ring Study, said that the results are statistically significant enough to apply for regulatory approval in individual countries as well as internationally.
“Most African countries require World Health Organisation [WHO] pre-qualification before they authorise health products and for that we need approval from either the Federal Drug Administration or the European Medicines Agency [EMA],” she said.
The Partnership for Microbicides will first seek EMA approval and expect the rings to be available on the market by 2018 at the earliest.
According to Nel, South Africa could get approval for the rings before other African countries, as it is one of the few countries on the continent with its own approval body – the Medicine Control Council – whereas many other African countries depend on the lengthy approval processes of the EMA or WHO.
In The Ring Study, HIV infections were reduced by 31% overall and by 37% in women older than 21.
The ASPIRE study found that the dapivirine vaginal ring reduced HIV infections by 27% overall but by 56% in women over the age of 21 and by 61% in women older than 25.
Baeten said these differences, common to both trials, relate to lower adherence rates in younger women – where the ring was not kept inside the vagina for the entire month.
The researchers measured adherence by testing the level of the drug in the blood of participants as well as the amount of dapivirine left in the rings themselves.
“We suspect that some women removed their rings before their clinic visit and re-inserted it before the next one,” he said. “Like with any medication it can only work if it is used.”
Although this method is not as effective as condoms, for example, Baeten said women, especially in high HIV-prevalence countries in Africa, need more than one option.
“Women’s preferences are not all the same – just as women have choices in contraception, they need choices for HIV prevention, too.”