- Chronic administration (defined as more than 14 days in total) of immunosuppressants or other immune-modifying drugs during the period starting six months prior to the first vaccine dose and up to 30 days post Dose 2. For corticosteroids, this will mean prednisone ≥ 20 mg/day or equivalent. Inhaled, topical and intra-articular corticosteroids are allowed.