We will exclude patients who fulfil any of the following criteria: - Use of systemic corticosteroids for any other indication than COVID-19 - Invasive mechanical ventilation for more than 48 hours - Invasive fungal infection - Fertile woman (< 60 years of age) with positive urine human gonadotropin (hCG) or plasma-hCG - Known hypersensitivity to hydrocortisone - A patient for whom the clinical team has decided not to use invasive mechanical ventilation - Consent not obtainable

We will exclude patients who fulfil any of the following criteria: - Use of systemic corticosteroids for any other indication than COVID-19 - Invasive mechanical ventilation for more than 48 hours - Invasive fungal infection - Fertile woman (< 60 years of age) with positive urine human gonadotropin (hCG) or plasma-hCG - Known hypersensitivity to hydrocortisone - A patient for whom the clinical team has decided not to use invasive mechanical ventilation - Consent not obtainable