- Negative serum pregnancy test at screening and negative urine pregnancy test on the day of admission to the inpatient phase for female subjects of childbearing potential. Females of childbearing potential must agree to use an efficacious method of birth control (birth control pills, injection hormonal contraceptive, implant hormonal contraceptive, hormonal patch, IUD, sterilization by hysterectomy or tubal ligation, spermicidal products and barrier methods such as cervical sponge, diaphragm, or condom) within two months of vaccination and during the entire study. Abstinence is acceptable. A woman is eligible if she is monogamous with a vasectomized partner.