ABSTRACT
The disease outbreak caused by the novel coronavirus, SARS-CoV-2, in December 2020 in Wuhan, China, has spread worldwide, threatening global health. While SARS-CoV-2 is now established as the cause of coronavirus disease 2019 (now named COVID-19), a respiratory illness, it has also become clear that some people with SARS-CoV-2 infection may exhibit no symptoms at all. We report the clinical characteristics and course of three asymptomatic patients who contracted SARS-CoV-2 infection on the cruise ship, Diamond Princess. The three patients did not have any symptoms at admission, however, all showed bilateral ground-glass opacities, predominantly distributed in the lung periphery, with occasional consolidation, on the plain chest radiograph. All three showed a smooth clinical course, and remained asymptomatic throughout the course of the infection. These cases serve to emphasize that patients without any symptoms could have COVID-19 pneumonia, and should be noted the possibility that mild cases and early onset of severe cases are included even in asymptomatic patients. According to one published paper, chest CT may be useful for early detection of COVID-19 pneumonia. In addition, other reports have documented the changes on chest CT associated with COVID-19 pneumonia from onset until recovery. From our experience of these cases and the published reports mentioned above, we consider that CT may be useful for the diagnosis of COVID-19 and determining the timing of onset of the disease.