Cytokine levels in sputum, not serum, may be more helpful for indicating the damage in the lung and the prognosis of severe COVID-19 - A case series.

PURPOSE:To describe the relationship between the severity of lung damage and cytokine levels in sputum, bronchoalveolar lavage fluid (BALF), serum. METHOD:Eight severe patients infected with coronavirus disease 2019 (COVID-19) were admitted and their cytokines and chest computed tomography (CT) were analyzed. RESULTS:Compared with in serum, IL-6 and TNF-α in sputum and in BALF show more directly reflect the severity of COVID-19 critical patients. The gradient ratio of IL-6 levels may predict the prognosis of severe patients. CONCLUSION:Cytokine levels in the sputum may be more helpful for indicating lung damage. Local intervention through the respiratory tract is expected to benefit patients with severe COVID-19.