Researchers will launch a large, multinational clinical trial this month to test the effectiveness and extended safety of a vaginal ring containing an experimental antiretroviral drug to prevent HIV infection in women. With a projected 3,476 participants in five countries, the MTN 020 study, otherwise known as, “A Study to Prevent Infection with a Ring for Extended Use (ASPIRE),” aims to determine whether the drug dapivirine can safely prevent HIV infection when continuously released in the vagina from a silicone ring replaced once a month. Results are expected in early 2015.