4.5  SARS-CoV-lung injury
The lungs of SARS-CoV infected patients were examined for histological and pathological changes due to the viral infection [35]. The histological changes include hepatization, severe lung consolidation, edema with pleural effusion, mucopurulent material in the tracheobronchial tree, focal hemorrhage, which was presented by the SARS-CoV affected patients [35,[46], [47], [48]]. The pathological changes include vascular edema, vascular injury, including small vessel vasculitis [49], desquamation of squamous metaplasia, and epithelial cells [50], pulmonary infarcts and vascular fibrin thrombi [51]. BOOP-like lesions such as the proliferation of fiber granulation tissue in alveolar spaces located subpleural and small airways. Also, the severity of the clinical manifestations depends on the stage of disease or onset of the disease which has been classified into three stages., edema, alveolar hemorrhage, fibrin exudation in alveolar spaces, hyaline membrane formation, and extreme bronchiolar injury indicate the acute phase, the first phase during the infection [50] (represented in Table 1).
Secondly, the proliferative phase characterized by cellular fibromyxoid-organizing exudates, widening of septae, and pneumocyte hyperplasia [52]. Formation of alveolar and septal fibrosis, where the severity of the fibrosis depends on the onset and duration of the disease [49,53].