COVID-19 Vaccination Effectively Reduces Pneumonia Severity as Assessed by Routine Chest Computed Tomography

Background: In China, the COVID-19 outbreak infected more than 80% of the population. Few trials have been conducted to assess the effectiveness of the China-manufactured vaccine against COVID-19. Purpose: The purpose of this study was to evaluate the severity of pneumonia in individuals with COVID-19 who were fully vaccinated, partially vaccinated, and unvaccinated, using routine chest computed tomography. Materials and Methods: We analyzed data from patients (aged >18 years) who were hospitalized due to COVID-19 pneumonia between December 2022 and January 2023. Patients who underwent routine chest CT scans were divided into three groups based on their vaccination status. The lobar involvement grading system (0-25) was used to assess the extent of lung injury. The primary outcome was either survival or death. The Pearson chi-square test, Fisher's exact test, and one-way ANOVA were used to compare clinical and imaging features. The receiver operating characteristic (ROC) curve analysis was used to calculate the area under the curve (AUC), sensitivity, and specificity of the CT severity score (CT-SS) in relation to the outcome. Results: Of the 94 patients with COVID-19 pneumonia, 39 patients (41%) were fully vaccinated, 14 (15%) were partially vaccinated, and 41 (44%) were unvaccinated. Among patients with COVID-19 pneumonia, the mean CT severity scores (CT-SS) were 5.9 ± 4.0, 6.5 ± 4.9, and 8.9 ± 4.5 for fully vaccinated individuals, partially vaccinated individuals, and unvaccinated individuals, respectively. The difference was statistically significant (p<0.05). CT-SS of 10.5 or higher was associated with severe pneumonia (100% sensitivity, 81.1% specificity, and an area under the curve of 0.92). Conclusion: COVID-19 vaccination leads to less severe pneumonia based on CT. Fully and partially vaccinated patients with COVID-19 pneumonia have less lung involvement compared to unvaccinated patients. Visual observation by CT imaging provides additional evidence to support the clinical effectiveness of vaccination.