- Immunosuppressive medications within 168 days prior to initial study vaccine administration, e.g., oral/parenteral corticosteroids, and/or cytotoxic medications. Not excluded: A participant using any of the following is not excluded: corticosteroid nasal spray for allergic rhinitis; or topical corticosteroids as prescribed by a physician for an acute, uncomplicated dermatitis; or over the counter medications (including topical corticosteroids for an acute, uncomplicated dermatitis); use of rapidly tapered steroids for an acute isolated condition, which does not include asthma within 28 days prior to vaccine administration.