8806 Russian patients demonstrate T cell count as better marker of COVID-19 clinical course severity than SARS-CoV-2 viral load

Abstract

The article presents a comparative analysis of SARS-CoV-2 viral load (VL), T lymphocyte count and respiratory index PaO₂:FiO₂ ratio as prospective markers of COVID-19 course severity and prognosis. 8806 patients and asymptomatic carriers were investigated in time interval 15 March-19 December 2020. T cell count demonstrated better applicability as a marker of aggravating COVID-19 clinical course and unfavourable disease prognosis than SARS-CoV-2 VL or PaO₂:FiO₂ ratio taken alone. Using T cell count in clinical practice may provide an opportunity of early prediction of deteriorating a patient's state.

Figure 1

Correlation between reversed PaO₂/FiO₂ ratio as an indicator of COVID-19 respiratory complications severity (the first item in ARDS score formula) and SARS-CoV-2 VL. In this and subsequent figures Confidence interval (CI) is 95%. Standard error of mean is showed as whiskers. Green dash-dotted line stands for the conditional border between asymptomatic carriers and symptomatic patients. Red dash-dotted line stands for the conditional border between extremely severe clinical cases and the rest of the patients. Percentage numbers in parentheses (green) correspond to the proportion of asymptomatic carriers whose manifestations fit into the conditional range to the left of the green line. Created in OriginPro ver. 9.2.196, https://www.originlab.com.

Figure 2

Correlation between leukocyte count in serum on logarithm of SARS-CoV-2 VL. Created in OriginPro ver. 9.2.196, https://www.originlab.com.

Figure 3

Correlation between B1 cell (light green line) and plasma cell (dark green line) counts in serum on logarithm of SARS-CoV-2 VL. Created in OriginPro ver. 9.2.196, https://www.originlab.com.

Figure 4

Distribution of SARS-CoV-2 VLs in severe clinical cases: (1) serious viral interstitial pneumonia with X-ray computer tomography opaqueness not less than 15% (469 cases, 5.33%); (2) severe respiratory failure of type 1 [either of PaO₂/FiO₂ ratio < 280 mmHg OR respiratory rate  > 30 min^–1 OR SpO₂ < 90% (ARDS score AS > 10–12)] (103 cases, 1.17%); (3) pulmonary embolism (48 cases, 0.55%); (4) immune response dysregulation known as “cytokine storm” (37 cases, 0.42%); (5) internal organ malfunction (11 cases, 0.12%); (6) transfer from general ward to ICU (202 cases, 2.29%); (7) lethal outcome (71 cases, 0.81%). Individual cases and statistical boxes are visualised along each other. Boxes: 25/50/75%. Whiskers: 5/95%. Horizontal lines are maximums/minimums, crosses stand for 1/99%. Created in OriginPro ver. 9.2.196, https://www.originlab.com.

Figure 5

T cell count dependence on logarithm of SARS-CoV-2 VL. Piecewise and smooth approximations are shown. Green dash-dotted line stands for the conditional border between asymptomatic carriers and symptomatic patients. Red dash-dotted line stands for the conditional border between extremely severe clinical cases and the rest of the patients. Percentage numbers in parentheses (green) correspond to the proportion of asymptomatic carriers whose manifestations fit into the conditional range to the left of the green line. (A) T killer (CD8⁺ cytotoxic lymphocyte) count (in serum) dependency on log₁₀VL. (B) Th1 helper (CD4⁺ CD94 + lymphocyte) count (in serum) dependency on log₁₀VL. (C) γδT and NKT lymphocyte counts (in serum) dependency on log₁₀VL. (D) CD8αα⁺ lymphocyte count (in pharynx MALT analysed in nasopharyngeal or oropharyngeal swabs) dependency on log₁₀VL. Created in OriginPro ver. 9.2.196, https://www.originlab.com.

Figure 6

T cell count dependence on respiratory factor reversed PaO₂/FiO₂ ratio. Linear piecewise approximation is shown. (A) T killer and NKT cell counts dependency on PaO₂/FiO₂ ratio. (B) γδT and CD8αα+ cell counts dependency on PaO₂/FiO₂ ratio. Created in OriginPro ver. 9.2.196, https://www.originlab.com.

Figure 7

Dependence of in-group mortality percentage on VL (A) and CF1 (B), experimental data and approximation. For detailed description please see the text. Created in OriginPro ver. 9.2.196, https://www.originlab.com.