Abnormalities of peripheral blood system in patients with COVID-19 in Wenzhou, China

•Patients with COVID-19 have abnormal blood routine examination results.•Dynamic surveillance of eosinophils is helpful in the prediction of severe COVID-19 cases.•NLR and MLR were combined for diagnosis of severe COVID-19, and its AUC was 0.925.•The delay to the start of the increase of eosinophil count predicts ominous outcome. In December 2019, coronavirus disease 2019 (COVID-19) was first found in Wuhan, China and soon was reported all around the world. All confirmed cases with COVID-19 in Wenzhou from January 19 to February 20, 2020, were collected and analyzed. Of the 116 patients with COVID-19, 27 were diagnosed as severe cases. Among severe cases, 9 were treated in ICU. The data of blood routine examination were analyzed and compared among common patients (as common group), severe patients admitted to intensive care unit (as severe ICU group) and severe patients not admitted to ICU (as severe non-ICU group). The blood routine examination results were dynamically observed in the above groups after admission. Patients with COVID-19 have lower counts of leucocytes, lymphocytes, eosinophils, platelets, and hemoglobin, but have higher neutrophil-lymphocyte ratio (NLR) and monocyte-lymphocyte ratio (MLR), which were compared with controls (P