Vaginal ring effective for HIV prevention

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Results from the HIV Open-label Prevention Extension (HOPE) study indicate that a monthly vaginal ring containing 25 mg of dapivirine could reduce HIV-1 incidence rates by approximately 30%.  The findings were reported earlier this month at the 10th IAS Conference on HIV Science.

The HOPE study was an open-label extension trial designed to provide participants of the A Study to Prevent Infection with a Ring for Extended Use (ASPIRE) with the opportunity to use the dapivirine ring for 1 year while researchers continued to collect information about its safety. The ASPIRE study originally compared the effectiveness of the dapivirine ring against a dapivirine injection and placebo.

Participants from the ASPIRE study were offered 12 months of access to the ring at 14 sites in Malawi, South Africa, Uganda, and Zimbabwe. The used rings were returned at each study visit and were tested for residual levels of dapivirine. HIV-1 serologic testing for HIV-1 RNA was done at each visit to determine incident infection. Incidence rates of the virus were compared to the expected amount by weighted bootstrap sampling of the placebo arm of ASPIRE.

The HOPE study, which began in July 2016 and concluded in August 2018, enrolled 1456 women who are not infected with HIV-1, median age 31. At baseline, 1342 (92%) accepted the vaginal ring and ring acceptance remained high throughout the study (90%, 89%, 87%, 83%, and 79% at Months 1, 2, 3, 6, and 9, respectively).  Following the return of the rings, 86% had residual dapivirine levels consistent with usage (> 0.9 mg released).

A total of 35 HIV-1 infections were observed during the study (incidence rate: 2.7 per 100 person-years, 95% CI 1.9-3.8). This was significantly lower than the expected incidence of 4.4 per 100 person years (95% CI 3.2-5.8) in the absence of the vaginal ring.

The authors of the study believe that their findings indicate that the dapivirine ring is effective at reducing HIV-1 incidence among high-risk women. Perhaps more importantly, their results indicate that women are interested in and are willing to adhere to the usage requirements of the ring. In places where access to health care is limited, a daily pill requirement may be burdensome, and the long-term effectiveness of the ring could serve an important role.