A vaginal ring with sustained release of an experimental antiretroviral drug provided partial protection against HIV infection in women, results from a large clinical trial has shown. Findings from the study are published in the New England Journal of Medicine

The objective of the ASPIRE study (MTN-020) was to determine whether dapivirine, an experimental antiretroviral agent, could safely and effectively prevent HIV infection through sustained release in the vagina via a silicone ring replaced every 4 weeks. The study included over 2,600 women ages 18-45 without HIV infection who were at high risk of being infected. The women, who were from sub-Saharan Africa (Malawi, South Africa, Uganda, Zimbabwe), were randomized to receive either the dapivirine ring or a placebo ring. 

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The study subjects received a HIV prevention services package at each study visit, which included HIV risk-reduction counseling, partner HIV testing, treatment of sexually transmitted infections, and condoms.

Among all women, the dapivirine ring reduced the risk of HIV infection by 27%. After excluding data where it was evident early on that many women were not returning for study visits or were using the ring inconsistently, the risk reduction was 37%. The data also showed the dapivirine ring reduced the risk of HIV infection by 61% among women ages ≥25 years. However, no statistically significant protection was seen in women <25 years; these women seemed to use the ring less consistently than others as measured by levels of dapivirine in the blood. 

Additional age-related analyses found that the dapivirine ring reduced the risk of HIV infection by 56% in women aged >21 years but no protection among women ages 18-21 years. The rate of adverse events was also found to be comparable among study subjects who received the dapivirine ring vs. placebo ring. 

Anthony S. Fauci, MD, director of the National Institute of Allergy and Infectious Diseases (NIAID), added, “Further research is needed to understand the age-related disparities in the observed level of protection.”

For more information visit nih.gov.