Contraception: The effects of benralizumab on the developing human fetus are unknown. For this reason, men and women of childbearing potential must agree to use adequate contraception (hormonal or barrier method of birth control; abstinence) prior to study entry and for the duration of study participation. Females of childbearing-age must have a negative pregnancy test result prior to receiving benralizumab. During the course of the study, if a woman becomes pregnant or suspects she is pregnant, she should inform the study staff and her primary care physician immediately. If a subject becomes pregnant, the investigational drug will be discontinued immediately, and the subject will be counselled as to how to resume approved therapeutic options in consultation with an obstetric provider.