She received high flow oxygen therapy but bilateral infiltration and oxygenation were deteriorated, so intubation and mechanical ventilator care started on day 4. Intravenous methylprednisolone (0.5 mg/kg/day daily) was also added. She had sustained high fever with rapidly increasing CRP (314 mg/L), WBC (21.79 × 103/µL), and persistent lymphopenia (0.5 × 103/µL). PaO2/FiO2 fell to 76, consistent with severe ARDS. After applying for the prone position according to the management of ARDS with the use of steroids, chest images and the oxygen demand began to be improved.