The CAPRISA 004 trial of tenofovir gel was the first to demonstrate the effectiveness of a microbicide. Its results, however, were not confirmed in FACTS 001, a second trial that assessed the same gel regimen, or in the VOICE trial of daily use of tenofovir gel.
In 2016, a vaginal ring containing another antiretroviral drug, dapivirine, became the first microbicide product to be shown effective against HIV in two clinical trials. In both trials, known as ASPIRE and The Ring Study, rates of HIV protection were higher among women older than 21, who tended to use the rings more consistently. Two open-label extension studies of the monthly dapivirine ring are under way, and the International Partnership for Microbicides is pursuing global and national regulatory approval to license the product in countries where women face the highest risk of acquiring HIV. Other clinical trials continue to explore the safety and effectiveness of various vaginal and rectal microbicide candidates. This section contains resource materials that highlight the recent history of clinical research on these microbicides, including studies of candidates that are no longer being assessed (for various reasons) and active candidate microbicides.