Abstract:

Objective To improve the pre-processing laboratory test method for the severe acute respiratory syndome，coronavirus （SARS-CoV-2） specimens， and to evaluate its effectiveness. Methods A total of 90 SARS-CoV-2 negative specimens and 30 SARS-CoV-2 positive specimens were collected. The specimens were divided into traditional group， modified 1 group， and modified 2 group， according to the test method. The specimens in traditional group were inactivated by using the guanidine salts and a 56 ℃， 30 minute water bath， followed by single tube oscillation， specimen de-identification， and single-handed lid opening for testing. The specimens in modified 1 group were inactivated by using the guanidine salts， followed by single tube oscillation， specimen de-identification， and single-handed lid opening for testing. The specimens in modified 2 group were inactivated by using the guanidine salts， followed by batch oscillation in vertical， horizontal， and 180-degree angle， specimen de-identification， and single-handed lid opening for testing. Real-time fluorescence quantitative PCR （RT-qPCR） method was used to detect the cycle threshold （Ct） values and detection time of the specimens in various groups； Spearman correlation analysis was used to analyze the correlation of Ct values between various groups； Blank-Altman method was used to perform the consistency test； the detection time of SARS-CoV-2 of the specimens in various groups was recorded. Results The Ct values of the specimens in modified 1 group were strongly correlated with those in traditional group （P<0.01）， and the correlation coefficient（r）=0.975 4 （0.966 2－0.982 1）. The Ct values of the specimens in modified 2 group were strongly correlated with those in traditional group （P<0.01）， r=0.986 2 （0.980 9－0.990 0）. The inter-group deviation of detecting SARS-CoV-2 negative specimens between modified 1 group and traditional group was 0.158 2（－0.613 7－0.930 1）， and the inter-group deviation of detecting SARS-CoV-2 positive specimens was 0.117 0 （－0.403 1－0.637 1）， indicating good consistency.The inter-group deviation between modified 2 group and traditional group for detecting SARS-CoV-2 negative specimens was 0.015 7（－0.550 4－0.581 8）， and for detecting SARS-CoV-2 positive specimens was 0.022 7（－0.454 1－0.499 4）， which indicated the good consistency. The detection time of 90 SARS-CoV-2 specimens in modified 1 group was 15 min， while the detection time of 90 SARS-CoV-2 specimens in modified 2 group was 10 min and the detection time of 90 SARS-CoV-2 specimens in traditional group was 45 min. Compared with traditional group， the detection time in modified 1 group was reduced by 67%and the detection time in modified 2 group was reduced by 11% . Conclusion The modified SARS-CoV-2 specimen testing method shows strong correlation and good consistency with the traditional testing method. It can save the detection time and improve the efficiency.

Key words: Novel coronavirus, Nucleic acid testing technique, Rapid diagnosis, Mean cycle threshold, Correlation coefficient