PRO 2000 in two different strengths was tested against an inert gel. It was hoped that the PRO 2000 gel would block HIV’s entry into cells and therefore prevent infection. After one year of use, however, there was no difference in the infection risk between the inert gel and the PRO 2000 gels.
This wasn’t the only microbicide in development. An antiretroviral microbicide is currently under trial in South Africa. Antiretroviral microbicides use a different mechanism of action than PRO 2000 – they may well be more effective than PRO 2000. Let’s hope.