Evolution of lobar distribution in patients with COVID-19
No statistically significant difference was found in the lobar distribution of pulmonary findings over different time intervals from symptom onset, but some trends were observed. For example, the proportion of patients with fewer than 3 lobes affected decreased in the first 10 days (Fig. 2a). The proportion of patients with three or more affected lobes was higher in all of the time intervals analyzed. Bilateral involvement was more prevalent than unilateral involvement with a trend toward an increase in the proportion of patients with bilateral CT abnormalities in the first 2 weeks after disease onset (Fig. 2b). Lower lobes have higher rates of involvement than the others, but the differences are not statistically significant (Fig. 2c).
Fig. 2 Evolution of lobar distribution of the (a) number of lobe affected, (b) unilateral and bilateral lobes affected, and (c) lung lobe affected in patients with COVID-19 within 21 days after disease onset. The time after disease onset (day) is categorized as 5 groups, i.e., days 0–3 (patient number = 37), days 4–7 (patient number = 69), days 8–10 (patient number = 53), days 11–14 (patient number = 49), and days 15–21 (patient number = 25)