- Sexually active individuals capable of becoming pregnant who are unable or unwilling to use effective form(s) of contraception during time enrolled on study. Effective forms of contraception include one or more of the following: intrauterine device (IUD), hormonal (birth control pills, injections, or implants), tubal ligation/hysterectomy, partner s vasectomy, barrier methods, (condom, diaphragm, or cervical cap), or abstinence. Males on the protocol must use an effective form of contraception at study entry.