fined by an increased extent of GGO, on early follow‐up CT (Pan et al., 2020). Pulmonary fibrous cords was reported in one particular patient that displayed signs of improvement, as the inflammatory secretions had been absorbed (Pan & Guan, 2020). Long‐term complications of COVID‐19 in patients with severe pneumonia might include an array of fibrotic changes often observed in the late stages of lung injury, for example, reticulation, interlobular septal thickening, and traction bronchiectasis (Kim, 2020).

2.2  Immune system
There have been several reports that indicated meager Cytolethal Distending Toxin‐induced lymphocytes, with a density as low as 200 cells/mm3 in three patients with SARS‐CoV infection (Chu et al., 2014; Zhou et al.,