- If the subject is female and of childbearing potential, she agrees to use acceptable contraception and remain on the same method during the study as they were using prior to entering the study, and not become pregnant for 28 days following the last vaccination. A woman is considered of childbearing potential unless post-menopausal or surgically sterilized. Acceptable contraception methods are restricted to effective devices [e.g., intrauterine device (IUD), NuvaRing®] or licensed hormonal products with use of method for a minimum of 30 days prior to vaccination, a monogamous relationship with a vasectomized partner and abstinence from sexual intercourse with men.