Severely ill patients with of the novel coronavirus disease 2019 (COVID-19) experience pathologic manifestations of acute respiratory distress syndrome (ARDS). Although clinical characteristics and lung CT analysis help in determining severity of illness, progressive pathologic changes that occur during the course of infection are not completely understood. Studies have shown high overlapping pathophysiology between severe influenza pneumonia and COVID-19 infections. Here, we attempted to

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... tulate how lung pathologic lesions evolve during progressive ARDS complications using a murine fatal influenza model. Based on these studies, we propose three pathologic stages that represent different stages of clinical illness in COVID-19 infections.