- Females must fulfill one of the following criteria: At least one year post-menopausal; Surgically sterile or have a surgically sterile partner; Willing to abstain from sexual intercourse; Willing to use a reliable form of contraception approved by the investigator (e.g., oral, implantable, transdermal or injectable contraceptives, intrauterine device (IUD), female condom, diaphragm with spermicide, cervical cap, or male condoms) for 30 days prior to first vaccination through 3 months after second vaccination