At the clinical recovery stage, severe patients with COVID‐19 had lower levels of total proteins (P < .05), albumin (P < .01), superoxide dismutase (SOD, P < .01), and lymphocytes (P < .01); higher levels of neutrophils (P < .05), C‐reactive protein (CRP, P < .01), and fibrinogen degradation products (FDP, P < .05); and a higher erythrocyte sedimentation rate (ESR, P < .01) than moderate patients (Table 3). Here, CRP is linked to COVID-19.