F2 and COVID-19: Up to date, some indicators such as hypersensitive C-reactive protein (h-CRP), procalcitonin (PCT), creatinine, LDH, aspartate aminotransferase (AST), hypersensitive cardiac troponin-I, prothrombin time, D-dimer, and lymphocyte count have provided supportive information to assess the severity of the disease and predict the prognosis of COVID-19 [8–10].