A 24-year-old man with exposure to a COVID-infected patient presented with fever and cough for 1 day and remains hospitalized currently. a–e CT scan shows GGO in the subpleural left lower lobe on day 1 (thick arrow). The overall total severity score is 1. f–j CT on day 4 shows enlarging GGO in left lower lobes (thick arrow). The overall total severity score is 3. k–o CT on day 8 shows increased GGO in bilateral lower lobes. The total severity score was 5. p–t CT obtained on day 11 shows bilateral ground glass opacities and linear opacities (thick arrow). The overall total severity score was 7. u–y CT obtained on day 15 shows improvement of bilateral lower lobe GGO and atoll sign (thick arrow). The overall total severity score is 5