Background The pulmonary artery area (PAA) is a valuable non-invasive method for the diagnosis of pulmonary hypertension. Purpose To compare the change in PAA in patients with COVID-19 with the computed tomography (CT) severity index using follow-up imaging. Material and Methods A total of 81 patients who were followed up and underwent CT assessment more than once at our hospital's pandemic department were evaluated retrospectively. Patients with progression were separated into three groups: progression ranging from mild-to-mild infiltration (Group A, CT severity index of 0-2); progression from mild to severe infiltration (Group B, CT severity index of 0-2 to 3-5); and progression from severe-to-severe infiltration (Group C, CT severity index of 3-5). The PAAs were calculated separately. Results The mean age was 56 +/- 12 years. In terms of those patients showing progression in the CT images, the number of patients in Groups A, B, and C was 29, 40, and 12 in the right lung; 32, 45, and 4 in the left lung; 23, 45, and 13 on both lungs, respectively. There was no significant difference between the main, right, and left PAAs in Group A (P > 0.05). In Group B, there were significant increases in the areas of the main, right, and left PAAs (P < 0.05). There were also significant increases in the areas of the right and main pulmonary arteries in Group C (P < 0.05). Conclusion PAAs increase as disease involvement advances in cases with COVID-19 pneumonia, which is thought to be correlated with progression.