Peripheral blood lymphocyte count is shown to be decreased in patients with COVID-19 in the early stage of the disease. The degree of lymphocyte count reduction is related to COVID-19 severity and could be used as an indicator to reflect the disease severity. Our aim was to investigate the value of lymphocyte count in determining COVID-19 severity and estimating the time for SARS-CoV-2 nucleic acid test results to turn negative. We retrospectively analyzed clinical data of 201 patients with severe and critical COVID-19. The patients were admitted to the West Campus of Union Hospital of Tongji Medical College of Huazhong University of Science and Technology. The data included age, gender, chronic disease, lymphocyte count, and SARS-CoV-2 nucleic acid test results. The age of patients in critically ill group was higher than in severely ill group (p = 0.019). The lymphocyte count of critically ill patients was lower than of severely ill patients. The cutoff value of lymphocyte count to distinguish between the critically ill and the severely ill was 0.735 × 109/L (p = 0.001). The cutoff value of lymphocyte count for SARS-CoV-2 nucleic acid test results turning negative in severely and critically ill patients with chronic diseases (hypertension, diabetes, and coronary heart disease) was 0.835 × 109/L (p = 0.017). The cutoff value of lymphocyte count for SARS-CoV-2 nucleic acid test results turning negative in severely and critically ill male patients was 0.835 × 109/L (p < 0.0001). Lymphocyte count could be an effective indicator to predict COVID-19 severity. It may also be useful in determining the time for nucleic acid test results to turn negative in COVID-19 patients with underlying chronic diseases or male COVID-19 patients with severe and critical conditions.

中文翻译：

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淋巴细胞计数在确定COVID-19的严重程度以及估计核酸测试结果变为阴性的时间时的价值。

在疾病的早期阶段，COVID-19患者的外周血淋巴细胞计数降低。淋巴细胞计数降低的程度与COVID-19严重程度有关，可以用作反映疾病严重程度的指标。我们的目的是研究淋巴细胞计数在确定COVID-19严重程度以及估计SARS-CoV-2核酸检测结果变为阴性的时间方面的价值。我们回顾性分析了201例重症和重症COVID-19患者的临床资料。患者入院为华中科技大学同济医学院附属协和医院西校区。数据包括年龄，性别，慢性病，淋巴细胞计数和SARS-CoV-2核酸检测结果。重症组患者的年龄高于重症组（p = 0.019）。重症患者的淋巴细胞计数低于重症患者。区分重症患者和重症患者的淋巴细胞计数的临界值为0.735×109 / L（p = 0.001）。在严重和重症的慢性病（高血压，糖尿病和冠心病）患者中，SARS-CoV-2核酸检测结果的淋巴细胞计数截止值为阴性，为0.835×109 / L（p = 0.017）。重症和重症男性患者中SARS-CoV-2核酸检测结果变为阴性的淋巴细胞计数的临界值为0.835×109 / L（p <0.0001）。淋巴细胞计数可能是预测COVID-19严重程度的有效指标。