ABSTRACT
Objective We explored and analyzed the evolutionary characteristics of COVID-19 cases numbers in different regions over time since the outbreak of the epidemic, so as to compare kinds of prevention and control measures and gain experience for public health management. Methods From the perspective of functional data, we applied functional principal component analysis to catch the primary temporal characteristics in cases number data over several periods, and performed hierarchical clustering on daily cases curves from various countries based on functional principal component scores to find the similarities among states. Results The first 3 functional principal components were retained for cumulative confirmed, cured and death cases numbers of all countries over each time period, each reflecting certain variability pattern among data at different times. On each period, 5 clusters were obtained, and the countries in clusters has changed over time. Conclusions The global epidemic has been fluctuating that cases numbers repeatedly grew at the end of June, September and November in 2020, which shows that there has been no effective measures so far. Changes in the clustering results also indicated that centralized isolation and strict management of imported persons are still the relative fast and effective intervention measures. © 2021, Publication Centre of Anhui Medical University. All rights reserved.
ABSTRACT
'Recurrence' of coronavirus disease 2019 (COVID-19) has triggered numerous discussions of scholars at home and abroad. A total of 44 recurrent cases of COVID-19 and 32 control cases admitted from 11 February to 29 March 2020 to Guanggu Campus of Tongji Hospital affiliated to Tongji Medical College Huazhong University of Science and Technology were enrolled in this study. All the 44 recurrent cases were classified as mild to moderate when the patients were admitted for the second time. The gender and mean age in both cases (recurrent and control) were similar. At least one concomitant disease was observed in 52.27% recurrent cases and 34.38% control cases. The most prevalent comorbidity among them was hypertension. Fever and cough being the most prevalent clinical symptoms in both cases. On comparing both the cases, recurrent cases had markedly elevated concentrations of alanine aminotransferase (ALT) (P = 0.020) and aspartate aminotransferase (AST) (P = 0.007). Moreover, subgroup analysis showed mild to moderate abnormal concentrations of ALT and AST in recurrent cases. The elevated concentrations of ALT and AST may be recognised as predictive markers for the risk of 'recurrence' of COVID-19, which may provide insights into the prevention and control of COVID-19 in the future.