- Chronic administration (defined as more than 14 days in total) of immunosuppressants or other immune-modifying drugs within six months prior to the vaccine dose. For corticosteroids, this will mean prednisone ≥ 20 mg/day (for adult subjects, ≥18 years of age) or ≥ 0.5 mg/kg/day (for paediatric subjects, aged 4-17 years), or equivalent. Inhaled and topical steroids are allowed