Assessing SARS-CoV-2 RNA Levels and Lymphocyte/T Cell Counts in COVID-19 Patients Revealed Initial Immune Status of Patients as a Major Determinant of Disease Severity

Background: The magnitude of SARS-CoV-2 infection, the dynamic changes of lymphocyte subsets and cytokines profiles of patients with the novel coronavirus disease (COVID-19) and their correlation with the disease severity remain unclear. Method: The clinical and laboratory results from 154 confirmed COVID-19 patients were collected and analyzed. Particularly, the SARS-CoV-2 RNA levels in patients were estimated using the Ct values of specific RT-PCR tests. The changes in lymphocyte subsets and cytokines profiles in the peripheral blood of COVID-19 patients were analyzed by flow cytometry and cytokine profiles by specific immunoassays. Findings: 154 patients were positive for SARS-CoV-2 RNA detection by RT-PCR and clinically examined up to 4 weeks after admission. The initial SARS-CoV-2 RNA Ct values at admission varied in patients but were comparable in the patient groups classified according to the age, gender, underlying diseases, and disease severity. However, 3 days after admission significant higher Ct values were found in patients that developed severe disease. In contrast, significantly reduced counts of T cells and T cell subsets were found in patients with old age and underlying diseases at admission and were characteristic for the development of severe COVID-19. Interpretation: Severe COVID-19 developed preferentially in patients with underlying compromised immunity and was not associated with initial virus levels. Higher SARS-CoV-2 RNA levels in severe cases were apparently a result of impaired immune control that was subsequently associated with dysregulation of inflammation in these patients. Early antiviral intervention, if available, may be necessary to prevent severe COVID-19 in immune impaired patients. Funding Statement: This work is supported by the Natural Science Foundation of Anhui Province (Grant no. 1608085MH162) and a grant from an unrestricted grant of the Rudolf-Ackermann-Stiftung (Stiftung fur Klinische Infektiologie) to O.W. Declaration of Interests: The authors disclose no conflicts of interest. Ethics Approval Statement: A written informed consent was regularly obtained from all patients upon admission into the Second People's Hospital, Fuyang, China. The study was approved by the Ethics Committee of the Second People's Hospital, Fuyang (Number 2020020004).