Performance Evaluation of the Serological Test and Dynamic Changes of Anti-2019-nCoV Antibodies Among COVID‐19 Patients

Background: Serological tests for anti-2019-nCoV antibodies have been developed, however, validation with clinical samples was insufficient and mixed. MethodsA total of 197 patients with COVID-19 hospitalized in the Wuhan Pulmonary Hospital and 114 healthy people were enrolled in this study. The IgM/IgG was measured by chemiluminescence detection kit and the performance of IgM/IgG was assessed through diagnostic test. A smooth spline function was used to fit a possible dynamic changes of antibody content.ResultsThe sensitivity and specificity to diagnose COVID-19 were 96.95% and 92.98% for IgG, and 65.99% and 98.25% for IgM, respectively. The period with the highest IgM positive rate (93.75%) was 11 to 13 days after the onset, while the IgG positive rate was almost 100% in the patients whose serum was collected 7 days after onset. Small differences were found in IgM content among mild/regular, severe and critical patients. IgG content in critical patients were highest in the 2-week post-symptom onset group, while the IgG in the severe patients were highest in the 15-28 days and more than 28 days post-symptom onset.ConclusionsSerological testing performed well in the diagnosis for COVID-19, and the positive rate and variance of IgG are higher than those of IgM.