Detectable serum SARS-CoV-2 viral load (RNAaemia) is closely associated with drastically elevated interleukin 6 (IL-6) level in critically ill COVID-19 patients

Xiaohua Chen; Binghong Zhao; Yueming Qu; Yurou Chen; Jie Xiong; Yong Feng; Dong Men; Qianchuan Huang; Ying Liu; Bo Yang; Jinya Ding; Feng Li

SARS-CoV-2 and SARS-CoV likely use the same angiotensin-converting enzyme 2 (ACE2) as the entry receptor [5] [6] [7] , but the clinical manifestations of two diseases were different. COVID-19 patients may develop mild or severe symptoms after infection. The mild patients show symptoms of fever, nonproductive cough, dyspnea, myalgia, fatigue, radiographic evidence of pneumonia; most of them appear to have a good prognosis. In contrast, some patients may develop severe pneumonia, acute respiratory distress syndrome (ARDS) or multiple organ failure [8] [9] [10] [11] . Importantly, in most moribund patients, SARS-CoV-2 infection is also associated with an inflammatory cytokine storm 4, 12 , which is mainly characterized by elevated plasma concentrations of interleukins 6 (IL-6). Indeed, several recent COVID-19 clinical studies all indicated that interleukins 6 levels is higher in severe group than those of mild group [12] [13] [14] [15] , suggesting that IL-6 might be used as a biomarker for severity evaluation. However, how the IL-6 level is quantitatively correlated with moribund patients is still unknown.