- Chronic administration (defined as more than 14 days) of immunosuppressants or other immune-modifying drugs on 14 consecutive days within six months prior to the first vaccine dose and up to one month after the last dose of the vaccine. (For corticosteroids, this will mean prednisone, or equivalent, ≥ 0.5 mg/kg/day. Inhaled and topical steroids are allowed).