Fig. 1.

The alterations of peripheral blood immune indices in different stages of the COVID-19 disease. There is a specific trend of changes in immune system effectors which is maintained from early infection to severe lethal stages of the disease. Neutrophil counts and the ratios of neutrophils to lymphocytes and to CD8+ T cells pursue an obviously increased pattern in COVID-19 patients who progress to the advanced stages of the disease. However, total lymphocytes and the number of CD4+ and CD8+ T cells tend to decrease from the early to severe stages. ARDS; Acute respiratory distress syndrome, Neu; Neutrophil, NLR: Neutrophil to lymphocyte ratio, N8R; Neutrophil to CD8+ T ratio.