Improved clinical symptoms and mortality among patients with severe or critical COVID-19 after convalescent plasma transfusion.

Coronavirus disease 2019 (COVID-19) is causing worldwide pandemic with no specific therapeutic agents, especially for severe or critical patients. To comprehensively evaluate the effectiveness, safety, and indications of convalescent plasma transfusion (CPT) therapy for severe or critical COVID-19 patients, we analyzed the clinical, laboratory, and radiologic characteristics of 1,568 patients from a single center, in which 138 patients received ABO-compatible CPT. The median time from the first symptom to CPT was 45 days. 2.2% and 4.1% of cases died in the CPT group and in the standard-treatment group, respectively. 2.4% and 5.1% of patients in the CPT and the standard-treatment group have been admitted to ICU eventually. 70% of the patients who had severe respiratory symptoms got improved and removed oxygen supports within 7 days after CPT. The viral loads and C-reactive protein (CRP) concentration significantly decreased (P<0.001), and the percentage of lymphocytes increased (P=0.006), 76.8% of cases received radiological improvements within 14 days after CPT. Patients with a higher percentage of lymphocytes and a lower percentage of neutrophils and CRP concentration respond better to CPT (P<0.05). Notably, for the patients who received CPT within 7 weeks after symptom onset, the median time from CPT to clinical improvements was approximately 10 days. But the time to clinical improvements was significantly prolonged for patients who received CPT later than 7 weeks after onset. Our study will provide important information for the clinical practice in COVID-19 treatment, as well as provide real-world observations and clinical data for the development of monoclonal antibodies.