Non-severe vs severe symptomatic COVID-19: 104 cases from the outbreak on the cruise ship “Diamond Princess” in Japan

Abstract

Background: The ongoing outbreak of 2019 novel coronavirus disease (COVID-19) is a global threat. Clarifying its clinical features such as risk factors for disease progression is a pressing issue. We analyzed the difference between non-severe and severe cases with COVID-19 as a result of the mass infection on a cruise ship “Diamond Princess” in Japan. Methods In this retrospective, single-center study, total 104 cases of laboratory-confirmed COVID-19 were enrolled from the mass infection on the cruise ship from 11th to 25th Feb, 2020, at Self-Defense Forces Central Hospital in Japan. Clinical records, laboratory data, and radiological findings were collected and analyzed. Clinical outcomes were followed up until 26th Feb, 2020. Findings Of the 104 patients, 47 were male. The median age was 68 years. During the observation period, eight patients deteriorated into the severe cases. Finally, 76 and 28 patients were classified as non-severe (asymptomatic, mild), and severe cases, respectively. Chest CT abnormalities were found in 43 in non-severe cases and 23 in severe cases. The prevalence of consolidation on chest CT scan and lymphopenia on the admission day was significantly higher in severe cases and in the eight cases which worsened into severe disease during the observation period. Interpretation The high proportion of non-severe cases corrects the assessment of the trend of the outbreak. Consolidation on chest CT scan and lymphopenia were possible risk factors for deterioration of COVID-19 and contribute to the clinical management. Funding Not applicable.