HIV topical microbicides: steer the ship or run aground.

Six HIV candidate microbicides are scheduled to enter 6 large-scale effectiveness trials in the next year. The selection of products for testing and the design of this group of trials should be reconsidered to provide an answer to a key question now before the field: Does a sulfonated polyanion, delivered intravaginally as a gel, block HIV attachment to target cells with sufficient potency to protect women from sexually acquired HIV infection?Paradoxically, entering more candidates into more trials may confuse or compromise efforts to identify an effective product. Instead, a single trial of the most promising product(s) best serves the current candidates while also preserving resources needed to promptly advance innovative new protective concepts into future large-scale trials.