a) Immunosuppressive drugs i) systemic glucocorticoids >/= 10 mg prednisone per day ii) cytotoxic drugs b) Investigational drugs within 30 days before, or planned during, the study c) Blood products within 3 months before, or planned during, the study d) Influenza vaccine within 9 months before the study e) Other vaccines within 30 days before, or planned during, the study