A monthly vaginal ring that releases a continual dose of dapivirine reduced the risk of HIV-1 infection by 61% among women 25 years of age and older, according to research published online in the New England Journal of Medicine.

“Vaginal rings can provide sustained and controlled release of medications,” wrote Jared M. Baeten, MD, PhD, professor of allergy and infectious diseases, epidemiology, and global health at the University of Washington School of Public Health in Seattle. “For HIV-1 prevention, an antiretroviral-containing vaginal ring could provide long-acting HIV-1 protection while reducing systemic exposure to the active pharmaceutical ingredient and delivering the anti-HIV-1 agent at the site of viral transmission.” The findings were also reported at the 2016 Conference on Retroviruses and Opportunistic Infections (CROI).

Dr Baeten and colleagues conducted a phase III, randomized, double-blind, placebo-controlled trial of the dapivirine ring among women in Malawi, South Africa, Uganda, and Zimbabwe. Over 2,600 women between 18 and 45 years of age were enrolled.

Continue Reading

Throughout the course of the study, 168 study participants developed HIV-1 infections, 71 in the dapivirine group and 97 in the placebo group. HIV-1 incidence was 27% lower in the dapivirine group among all trial participants. After excluding data for women who did not use the ring consistently or did not return for study visits, the researchers found that HIV-1 incidence in the dapivirine group was lower than in the placebo group by 37%. The highest rates of HIV-1 protection were recorded in study participants 21 years of age or older.

“Longer-acting methods of drug delivery, such as vaginal rings, may simplify the use of antiretroviral medications and provide HIV-1 protection,” wrote Dr Baeten. “Across trials of tenofovir-based prophylaxis, a sizable proportion of participants were not adherent, a finding that emphasizes the need for additional options, particularly ones that women can control.”


  1. Baeten JM, Palanee-Phillips T, Brown ER, et al. Use of a vaginal ring containing dapivirine for HIV-1 prevention in women. New Engl J Med. 2016; doi: 10.1056/NEJMoa150611