4. Women who are not post-menopausal (≥ 50 years of age and at least one year post last menses) or surgically sterile must have a negative urine pregnancy test at vaccination; will be advised through the Informed Consent process to avoid becoming pregnant over the duration of the study, and must assert that they will employ an effective form of birth control for the duration of the study. Acceptable forms of birth control are: credible history of abstinence from heterosexual activity, hormonal contraceptives (oral, injectable, implant, patch, ring), double-barrier contraceptives (condom or diaphragm, with spermicide), and intrauterine device (IUD)