Objective:To investigate the clinical and imaging features of population receiving opportunistic screening for lung cancer and in convalescent stage of COVID-19.Methods:Cross-sectional study and analysis was performed on the patients who underwent chest low-dose CT examination for cancer prevention in Cancer Hospital of Chinese Academy of Medical Sciences from December 28, 2022 to January 19, 2023. All the patients completed the COVID-19 questionnaire. A total of 334 questionnaires were sent out, all of which were recovered, and 321 valid questionnaires were collected, among them, 293 questionnaires were included in the analysis. Statistical analysis was conducted according to the questionnaire information, clinical symptoms and chest CT imaging results. The potential influencing factors of COVID-19 infection were explored, and the imaging characteristics of COVID-19 infection and early stage of lung cancer were compared.Results:A total of 293 patients underwent lung cancer screening during the convalescent stage of COVID-19 infection. A total of 231 (78.8%) cases had cough and 228 (77.8%) cases had fever. 214 (73.0%) cases still had clinical symptoms within 2 weeks after nucleic acid or antigen test showing negative, especially for cough in 171 (58.4%) cases, fatigue in 79 (25.3%) cases and sputum in 73 (24.9%) cases. There were 54 (18.4%) cases with positive chest CT changes. The main imaging findings showed that there were 46 cases with new patchy shadows, 25 cases with linear opacities, 10 cases with ground-glass opacities, 10 cases with nodular like shadows and 2 cases with consolidation, and most lesions were in the subpleural area of both lungs. Univariate analysis showed that positive CT findings were correlated with the time from positive detection of COVID-19 to screening ( P=0.026), age ( P<0.001) and underlying diseases ( P=0.006). Multivariate analysis showed that age≥65 years old ( OR=6.425, 95% CI: 2.688-15.358; P<0.001) and underlying diseases ( OR=2.292, 95% CI: 1.120-4.691; P=0.023) were risk factors for pulmonary imaging changes of COVID-19 infection. For lung cancer opportunistic screening, 36 (12.3%) cases showed ground-glass opacities in bilateral or unilateral lung lobes, among which 4 cases were suspected to be atypical adenomatous hyperplasia and 2 cases s were suspected to be early stage of lung cancer. Conclusions:Abnormal clinical symptoms and chest CT findings are still observed in the patients during the convalescent stage of COVID-19 infection. Age≥65 years, underlying diseases were the high-risk factors for the changes in chest CT imaging after COVID-19 infection. Attention should be paid to the differential diagnosis of chest CT findings between changes in the convalescent stage of COVID-19 and early stage of lung cancer.