Abstract:Objective To explore the characteristics of symptoms and signs in patients with initial and recurrent COVID-19 infections from the perspective of the Zang-Xiang syndrome differentiation system, providing clinical data support for Chinese Medicine treatment of COVID-19 infection. Methods A total of 141 patients who tested positive for COVID-19 nucleic acid by throat swab at the Infectious Disease Department of Nanjing Hospital of Chinese Medicine from June 1 to August 31, 2023, were selected as the research subjects, including 40 cases (28.4%) of initial infection and 101 cases (71.6%) of recurrent infection. Statistical analysis and data mining methods such as frequency statistics, cluster analysis, and factor analysis were used to investigate the characteristics of symptoms and signs in initial and recurrent COVID-19 infections. Results The age of initial infection ［35.50 (26.25, 62.75) years］ was not statistically different from that of recurrent infection ［35.50 (26.25, 62.75) years］ (Z=0.686, P=0.492). The body temperature of initial infection ［38.50 (38.00, 39.20)℃］ was higher than that of recurrent infection ［38.00 (37.40, 38.50)℃］, with a significant difference (Z=3.619, P＜0.01). Results of frequency statistics, cluster analysis, and factor analysis showed that the primary location of disease in initial COVID-19 infection was in the lungs, which can also involve the heart, spleen and stomach, while rarely affecting the liver and kidney. The nature of the disease is predominantly heat and dampness, which can also involve cold, Qi stagnation, Qi deficiency, Yin deficiency, and Yang deficiency. Patients with recurrent COVID-19 infection had disease locations in the lungs, involving the upper, middle, and lower jiao organs such as the heart, spleen, stomach, liver, gallbladder, and kidney, with the nature of the disease being primarily dampness, heat, cold, Qi deficiency, Qi stagnation, and Yin deficiency. Conclusion Both initial and recurrent COVID-19 infections primarily affect the lungs. Patients with initial infection exhibit more concentrated symptoms, while those with recurrent infection demonstrate complex characteristics involving multiple disease locations and natures, with generally milder symptoms.