Practice and exploration of novel coronavirus nucleic acid detection in designated hospitals

Objective: To explore the related problems and solutions in nucleic acid detection of COVID-19 patients at the present stage, and to provide reference for clinical laboratories. Methods: A total of 462 patients admitted from April 1 to April 10 were selected and their basic Ct values and time changes were analyzed. The false-negative test results caused by sample collection from March 20 to March 31 and from April 1 to April 10 were statistically analyzed, respectively. A total of 213 clinical samples were selected for parallel detection using reagents A and B to compare the differences between them. According to relevant documents, make the reinspection standard operation procedure (SOP) document of suspicious samples. According to the quality control method of quantitative test, weak-positive control was prepared and tested 5 batches every day for 4 days, and 20 groups of data were obtained and used as the initial data to make quality control charts. Results: The median Ct values of ORF1ab and N gene in 462 patients were 24.50 (20.58-32.10) and 23.38 (19.43-31.24), respectively. In 184 patients with Ct value less than 30, the median time for Ct value to rise above 30 was 6 days (4-8 days). The sampling unqualified rates were 12.4% and 2.4% in the early and late stages, respectively, and the difference was statistically significant (P