Viral Load Dynamics and Clinical Disease Severity in Patients with SARS-CoV-2 Infection

Background: The SARS-CoV-2 epidemic is currently spreading across the world. A better knowledge of viral loads at different stages of disease progression would help inform clinical management and prevent nosocomial transmission. Methods: More than 3,000 respiratory, stool, serum and urine samples were collected from 96 laboratory-confirmed COVID-19 patients. SARS-CoV-2 RNA viral load was measured, and the relationship between clinical data and disease severity was analyzed. Findings: All patients were confirmed by testing respiratory specimens, and 54.22% of the patients had positive in stool and 39.36% had positive in serum. The median virus duration in stool (21 days, IQR 17-29 days) was significantly longer than in respiratory (18 days, IQR 13-28 days) and serum samples (16 days, IQR, 13-20 days) (p<0.001). The median virus duration in the respiratory samples of severe patients (21 days, IQR, 14.5-28.25 days) was significantly longer than in mild patients 13.5 days (IQR, 9.5-20.5 days) (p<0.001). In the mild group, the viral loads peaked in the second week from disease onset, whereas, viral load continued to be high during the third week in the severe group. Age and sex were identified as independent factors of viral duration. Interpretation: Our study suggests that respiratory samples are still the most effective for detecting SARS-CoV-2, while it is necessary to strengthen the management of stool samples in the prevention and control of the epidemic, especially in the later stage of the disease. As SARS-CoV-2 persists longer with higher load, and peaks later in the respiratory tissue of severe patients, the rational use of antiviral drugs is needed to shorten the duration of the virus and reduce the occurrence of severe cases. Funding Statement: This work was supported by the China National Mega-Projects for Infectious Diseases (grant number 2017ZX10103008 and 2018ZX10101001); and the National Natural Science Foundation of China (grant numbers 81672014 and 81702079). Declaration of Interests: All authors: No reported conflicts. Ethics Approval Statement: This study conformed to the ethical guidelines of the 1975 Declaration of Helsinki and was approved by the Institutional Review Board of the First Affiliated Hospital of Zhejiang University