Objective:To evaluate the clinical efficacy of Xuebijing combined with human immunoglobulin for the treatment of severe and critically ill patients with coronavirus disease 2019 (COVID-19).Methods:A retrospective study was conducted. The clinical data of 65 patients with severe and critical COVID-19 admitted to Chongqing Public Health Medical Center and Chongqing Three Gorges Central Hospital from January 2020 to March 2020 during the period of supporting to combat COVID-19 by the medical team of the Second Affiliated Hospital of Chongqing Medical University and Chongqing Hospital of Traditional Chinese Medicine were analyzed. According to different treatment regimens, patients were divided into conventional treatment group (conventional antivirus, anti-infection and symptomatic support treatments), Xuebijing group (Xuebijing was applied to patients with elevated inflammatory cytokines) and combination group (Xuebijing combined with human immunoglobulin, human immunoglobulin was applied to patients with low immunity indicated by monitoring results of lymphocytes and their subsets). The improvement of blood routine examination, blood gas analysis, myocardial enzyme spectrum, liver and kidney function, lymphocytes and their subsets and cytokines as well as severity score in three groups before and after treatment were observed. Kaplan-Meier method was used to draw the 28-day survival curve of each group, and the cumulative survival rate among the groups was compared.Results:Among the 65 severe and critically ill COVID-19 patients, only 20 patients received conventional treatment, 22 patients were treated with Xuebijing based on conventional treatment, and 23 patients were treated with Xuebijing combined with human immunoglobulin based on conventional treatment. Before treatment, CD4 + T cell count in combination group was higher than other two groups, and interleukin-6 (IL-6) was lower than other two groups, while other indicators showed no statistically significant differences among the three groups, suggesting that the baseline of the three groups was relatively balanced before treatment. The patients in the conventional treatment group were relieved after treatment, and it was characterized by that the acute physiology and chronic health evaluation Ⅱ (APACHEⅡ) score and lactate dehydrogenase (LDH) were significantly lower than those before treatment [APACHEⅡ score: 5.20±2.74 vs. 6.20±1.93, LDH (μmol·s -1·L -1): 4.1±1.0 vs. 4.7±0.9, both P < 0.01], but there was still liver damage, which was manifested as higher aspartate aminotransferase (AST) than that before treatment [U/L: 30.5 (23.8, 41.5) vs. 21.0 (17.0, 34.0), P < 0.05]. In Xuebijing group, the respiratory function and immunity of patients were improved after treatment, and the improvement degree of the ratio of CD4 + T cell was more significant than that in the conventional treatment group (4.86±6.31 vs. -0.95±12.38, P < 0.05). However, the patients still lived with an "inflammatory storm" and liver damage after treatment. It was shown that IL-4 was significantly higher than that before treatment (ng/L: 2.57±1.15 vs. 1.92±1.04, P < 0.05), while albumin (ALB) decreased significantly compared with before treatment [g/L: 33.0 (30.5, 35.6) vs. 36.2 (32.1, 41.4), P < 0.01]. While the treatment of Xuebijing combined with human immunoglobulin could improve patients' respiratory function and enhance their immunity more effectively, it was shown that arterial partial pressure of oxygen (PaO 2), oxygenation index (PaO 2/FiO 2), T lymphocyte count, ratio of CD4 + T cell, CD4 + T cell count, CD8 + T cell count and CD4 +/CD8 + ratio were significantly higher than those before treatment, while ALB, IL-6, APACHEⅡ score and sequential organ failure assessment (SOFA) score were significantly lower than those before treatment. T lymphocyte count, the ratio of CD4 + T cell and IL-6 in combination group were improved more significantly than those in conventional treatment group and Xuebijing group [T lymphocyte count (×10 9/L): 310.68±359.28 vs. 46.54±240.01, 81.59±256.76; ratio of CD4 + T cell: 14.53±14.49 vs. -0.95±12.38, 4.86±6.31; IL-6 (ng/L): -25.53±39.05 vs. -1.75±5.45, 12.78±44.81], PaO 2/FiO 2 was improved more significantly as compared with the Xuebijing group [mmHg (1 mmHg = 0.133 kPa): 146.31±109.73 vs. 59.41±87.70], and the differences were statistically different (all P < 0.05). Conclusion:The combination of Xuebijing and human immunoglobulin for the treatment of patients with COVID-19 can improve patients' respiratory function, reduce "inflammatory storm", enhance immunity, and alleviate severity of patients' condition.