The Food and Drug Administration on Monday gave approval to Australia-based Starpharma to begin human trials in the U.S. of its HIV microbicide gel called VivaGel, CNN.com reports. The compound was shown to be 100% effective in animals in preventing HIV, genital herpes, and chlamydia infections. The gel will be studied in women for the prevention of vaginal HIV infections. The company hasn't commented on whether the compound will be evaluated to prevent HIV infections through anal sex. Starpharma officials say if the trials are successful, a prescription-only version of the product could be available within three years, with an over-the-counter version possible in about five years.