- Females Only: Female participants of childbearing potential willing to use effective contraception for the duration of the trial. Reliable methods of contraception include: hormonal birth control, condoms with spermicide, diaphragm with spermicide, surgical sterilization, intrauterine device, and abstinence (6 months or longer since last sexual encounter). All female participants will be considered having childbearing potential except for those with hysterectomy, tubal ligation, tubal coil (at least 3 months prior to vaccination), or post-menopausal status documented as at least 1 year since last menstrual period.