Results from two large-scale studies of a vaginal ring that releases the antiretroviral medicine dapivirine to prevent HIV among women have shown protection of around 30% against HIV. The results are encouraging and show the urgent need to expand investment in research and development for female-controlled methods of HIV prevention.
Although less effective than hoped for, the results are the first to show that a sustained release mechanism for antiretroviral medicine is feasible, safe and partially effective in preventing HIV infection among women. Follow-up studies are needed to build on these results and there is a need to better understand how to optimise the HIV prevention effect and support adherence.
‘Women urgently need better options for HIV prevention, especially options that allow them greater control,’ said Luiz Loures, Deputy Executive Director, UNAIDS. ‘The path to an effective microbicide has been a long one. The important results from these two studies take us one step closer towards an HIV prevention product that could protect millions of women worldwide.’
The two studies, presented on 22 February 2016 at the annual Conference on Retroviruses and Opportunistic Infections, being held in Boston, USA, were carried out across four African countries and recruited more than 4500 women. Each participant was randomly assigned to use either an active ring that slowly released the antiretroviral medicine dapivirine over the course of one month or to receive an inactive placebo ring containing no medicine. The risk of HIV infection was compared between women using the active rings and women using the placebo rings after two to four years of follow-up.
The ASPIRE/MTN-020 trial was carried out by the Microbicide Trials Network and the Ring Study/IPM 027 trial was carried out by the International Partnership for Microbicides. As the two trials were independent, it is encouraging that they achieved similar results (27% protection in ASPIRE and 31% protection in the Ring Study). Despite the high levels of adherence to the ring (82% in ASPIRE and 73% in the Ring Study), the results are lower than hoped for.
Another important finding from both studies was that there was little protection against HIV for women aged 21 years and below, with better protection for women 22 years and above. At least part of this difference was explained by better adherence in the older age group.
Young women in sub-Saharan Africa remain most affected by HIV. Around 79% of all women living with HIV (aged 15 years and older) live in the region. The results from this, and previous studies into female-controlled HIV prevention methods, reinforce the urgent need to find better HIV prevention methods that offer more choices for women.