High proportion of mild-type patients
Among the 78 cases, there were 24 cases of mild type (30.8%) which mean those patients had positive real-time RT-PCR SARS-CoV-2 tests, while chest CT was normal. In the review of several recent published literature of COVID-19 in Wuhan, China, all patients reported in articles had ground-glass opacities in the lungs. Huang et al reported 41 infected cases in Wuhan, all had pneumonias [1]. Chen et al reported 99 confirmed cases in Wuhan with 74 bilateral pneumonias and 25 unilateral pneumonias [19]. However, the most recent report from Guangzhou had similar findings, which showed 23.6% confirmed patients without abnormalities on chest CT [20]. To further explore our data, we found several characteristics. Nine cases had a short time interval from onset to the latest CT examination with a range of 0–7 days, which indicated that the chest CT could be normal at the early phase. Another 9 cases had a longer time interval from onset to the latest CT scan with a range of 8–19 days. The negative findings may not relate to the shorter onset time. It remains to be further explored whether the CT negativity may relate to the degree of infection and autoimmunity. Finally, the last 6 patients had no symptoms. These patients were negative in both clinical and imaging, suggesting that some cases were potential sources of infection, which should be paid more attention to.