The most widely studied microbicides were formulated as gels used either daily or before and after sex. Poor adherence to these study regimens heightened interest in long-acting microbicide candidates, such as a vaginal ring that slowly releases an antiretroviral drug over time.
In 2016, ASPIRE and The Ring Study, two trials of a vaginal ring containing the antiretroviral drug dapivirine, showed a modest protective effect against HIV, with greater efficacy among subgroups of participants with evidence of higher adherence. Follow-up studies suggest that women are willing to use the ring, which is being considered for licensure.
Additional vaginal and rectal microbicide candidates are moving through the research pipeline. Scientists believe that a microbicide that contains a combination of different active drugs will likely have the greatest impact on the HIV epidemic, and some vaginal products are being designed to prevent both HIV infection and unwanted pregnancies.
This section of the toolkit provides essential background and reference materials on the different types of microbicides, the need for effective products for women and men, the status of microbicide research, and how microbicides fit into the larger field of HIV prevention.