The proposed pulmonary inflammation load score was higher in patients with severe COVID-19 in comparison with patient with mild disease. The optimal inflammation load score threshold for identifying severe patients was 19.5, with 83.3% sensitivity and 94% specificity. Summary statement The chest CT severity score could be used to rapidly identify patients with severe forms of COVID-19. Background: Quantitative and semi-quantitative indicators to evaluate the severity of lung inflammation in Coronavirus Disease 2019 (COVID-19) could provide an objective approach to rapidly identify patients in need of hospital admission. Purpose: To evaluate the value of chest computed tomography severity score (CT-SS) in differentiating clinical forms of COVID-19. Materials and Methods: Inclusion of 102 patients with COVID-19 confirmed by positive real-time reverse transcriptase polymerase chain reaction on throat swabs underwent chest CT (53 men and 49 women, 15-79 years old, 84 cases with mild and 18 cases with severe disease). The CT-SS was defined by summing up individual scores from 20 lung regions; scores of 0, 1, and 2 were respectively assigned for each region if parenchymal opacification involved 0%, less than 50%, or equal or more than 50% of each region (theoretical range of CT-SS from 0 to 40). The clinical and laboratory data were collected, and patients were clinically subdivided according to disease severity by the Chinese National Health Commission guidelines. Results: The posterior segment of upper lobe (left, 68/102; right, 68/102), superior segment of lower lobe (left, 79/102; right, 79/102), lateral basal segment (left, 79/102; right, 70/102) and posterior basal segment of lower lobe (left, 81/102; right, 83/102) were the most frequently involved sites in COVID-19. Lung opacification mainly involved the lower lobes, in comparison with middle-upper lobes. No significant differences in distribution of the disease were seen between right and left lungs. The individual scores of in each lung, as well as the total CT-SS were higher in severe COVID-19 when compared with mild cases (P＜ 0.05. The optimal CT-SS threshold for identifying severe COVID-19 was 19.5 (area under curve, 0.892), with 83.3% sensitivity and 94% specificity. Conclusion: CT-SS could be used to quickly and objectively evaluate the severity of pulmonary involvement in COVID-19 patients.

35Background: To explore the cellular immunity and cytokines status of NCP patients and to predict 36 the correlation between the cellular immunity levels, cytokines and the severity of patients. 37Methods: 123 NCP patients were divided into mild and severe groups. Peripheral blood was 38 collected, lymphocyte subsets and cytokines were detected. Correlation analysis was performed on 39 the lymphocyte subsets and cytokines, and the differences between the indexes of the two groups 40 were analyzed. 41Results: 102 mild and 21 severe patients were included. Lymphocyte subsets were reduced in two 42 groups. The proportion of CD8 + T reduction in the mild and severe group was 28.43% and 61.9%, 43 respectively; The proportion of B cell reduction was 25.49% and 28.57%; The proportion of NK 44 cell reduction was 34.31% and 47.62%; The detection value of IL-6 was 0 in 55.88% of the mild 45 group, mild group has a significantly lower proportion of patients with IL-6 higher than normal than 46 severe group; There was no significant linear correlation between the lymphocyte subsets and 47 cytokines, while significant differences were noticed between the two groups in CD4 + T, CD8 + T, 48 IL-6 and IL-10. 49Conclusions: Low levels of CD4+T and CD8+T are common in severe NCP. IL-6 and IL-10 levels 50were higher in severe patients. T cell subsets and cytokines can be used as one of the basis for 51 predicting the transition from mild to severe. Large number of samples are still needed to confirm 52 the "warning value" of CD4 + T, CD8 + T IL-6 and IL-10. 53

We explored the relationships between lymphocyte subsets, cytokines, pulmonary inflammation index (PII) and disease evolution in patients with (corona virus disease 2019) COVID-19. A total of 123 patients with COVID-19 were divided into mild and severe groups. Lymphocyte subsets and cytokines were detected on the first day of hospital admission and lung computed tomography results were quantified by PII. Difference analysis and correlation analysis were performed on the two groups. A total of 102 mild and 21 severe patients were included in the analysis. There were significant differences in cluster of differentiation 4 (CD4 + T), cluster of differentiation 8 (CD8 + T), interleukin 6 (IL-6), interleukin 10 (IL-10) and PII between the two groups. There were significant positive correlations between CD4 + T and CD8 + T, IL-6 and IL-10 in the mild group (r 2 = 0Á694, r 2 = 0Á633, respectively; P < 0Á01). After 'five-in-one' treatment, all patients were discharged with the exception of the four who died. Higher survival rates occurred in the mild group and in those with IL-6 within normal values. CD4 + T, CD8 + T, IL-6, IL-10 and PII can be used as indicators of disease evolution, and the PII can be used as an independent indicator for disease progression of COVID-19.