South Africa’s Medical Research Council (MRC) is investigating whether more than 20 women who have become HIV positive during a scientific trial, had been infected as a result of use of the microbicide that was being tested to prevent infection in the first place. MRC president Professor Anthony Mbewu confirmed that on January 31 the US-based agency CONRAD had informed the MRC that its international clinical trial of a vaginal microbicide cellulose sulphate (Ushercell) would have to be terminated early due to concerns by the Independent Safety Monitoring Committee that the microbicide might actually be increasing HIV transmission rather than preventing it.