The silicone vaginal ring continuously releases the antiretroviral drug, dapivirine.
Image credit: International Partnership for Microbicides
In the US, the Centers for Disease Control and Prevention (CDC) estimate that 1,218,400 people aged 13 years and above are living with human immunodeficiency virus (HIV) infection, an estimated 12.8% of whom are unaware of their condition.
In 2014, 25.8 million people in sub-Saharan Africa had been infected with HIV, half of whom were women.
A quarter of new cases in the region occur among adolescent girls and young women.
For this reason, finding effective tools to prevent the spread of infection is considered essential.
The ASPIRE HIV protection study, also known as MTN-020, was set up to investigate the effect of vaginal rings that release drugs.
This was a large clinical trial involving 15 sites in four sub-Saharan African countries: Malawi, South Africa, Uganda and Zimbabwe.
ASPIRE looked at whether a silicon vaginal ring that continuously released the drug dapivirine could protect against HIV infection. The ring was replaced every 4 weeks.
Starting in 2012, the study enrolled 2,629 women aged 18-45 years who did not have HIV but who were at high risk for HIV infection. Data collection continued until September 2015.
The women were randomly assigned to two groups. One group received a ring containing 25 mg of dapivirine, and a control group received a placebo ring.
Consistent use offers safe and effective protection
Participants and their partners also received a package of HIV prevention services at each study visit, including HIV risk-reduction counseling, HIV testing, treatment of sexually transmitted infections (STIs) and free condoms.
The risk of HIV infection was 27% lower overall among women using the ring, and it was 61% lower among women aged 25 years and over. Women in the over-25 age group used the ring most consistently.
After discounting the data for two sites on which adherence to the trial was very low, the reduction in risk of HIV was 37% overall.
The dapivirine ring did not provide any statistically significant protection in those aged under 25 years. The lower amount of dapivirine in their blood samples suggest that they did not use the ring consistently.
Further analyses indicated that the ring reduced the risk by 56% in women over 21 years, but not at all among those aged 18-21 years.
More research could reveal whether this lack of protection is due to behavior, biology or a combination.
The treatment did not increase the rate of adverse medical events, nor did it affect the frequency of antiretroviral resistance in women who acquired HIV.
Dr. Anthony S. Fauci, director of the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health (NIH) and the primary funder of the trial, says:
"Women need a discreet, long-acting form of HIV prevention that they control and want to use. This study found that a vaginal ring containing a sustained-release antiretroviral drug confers partial protection against HIV among women in sub-Saharan Africa. Further research is needed to understand the age-related disparities in the observed level of protection."
Another major study, The Ring Study, also found an overall effectiveness of 31% for the same treatment, with a slightly reduced risk of HIV infection among women aged over 21 years.
Outside experts will help to determine the next steps for research on the dapivirine ring, which was developed by the International Partnership for Microbicides (IPM).
Medical News Today reported on the development of a vaginal ring containing acyclovir, which researchers hope will be effective against HIV and STIs.