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.

Summary 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.