Objectives: To compare the temporal lung changes in Coronavirus Disease 2019 (COVID-19) pneumonia in younger (< 40 years) and older (≥ 40 years) adults and determine appropriate Computed Tomographic (CT) follow-up time.

Materials and methods: The chest CT images of 100 laboratory-confirmed SARS-CoV-2 infected patients were analyzed retrospectively, including 43 younger patients (27.95 ± 4.95 years) and 57 older patients (59.6 ± 10.71 years). The CT score and major CT findings were evaluated.

Results: An abnormal (positive) CT status in 33/43 (76.7%) of younger patients and 51/57 (89.5%) of older patients was recorded, when the initial CT was done at 4.88 ± 2.22 days and 5.75 ± 1.97 days respectively. On the initial scans, pure Ground-Glass Opacities (GGO) and crazy-paving patterns were common. On subsequent follow-up scans, the GGO plus reticulations, reticular pattern and pleural thickening were more commonly seen with significantly higher frequency in older patients. The mean total CT severity score in older patients was greater for initial as well as subsequent follow-up scans (all P<0.001). For the younger patients, the CT score reached a peak at 12 days and nadir at 30 days after symptom onset, while in older patients the peak CT score was reached at 14 days and lowest CT score was reached at 37 days.

Conclusion: The disease appeared to be milder in the younger population. The elderly patients are more likely to have extensive lung lobe involvement, interstitial and reticular changes, and pleural thickening. The appropriate follow-up time of CT scans is during the second week (approximately 12 days for younger patients and approximately 14 days for older patients) and after the fifth week (approximately 30 days for younger patients and approximately 37 days for older patients).