- of childbearing potential with a negative serum pregnancy test at screening and Day 1, that, if sexually active, agree to use one of the appropriate medically accepted methods of birth control from the date of screening until 7 months after the last dose of RBV in addition to the consistent and correct use of a condom. Patients must agree not to breast-feed at any time from the date of screening until 7 months after the last dose of RBV.