Should the nucleic acid transport media be left behind for the “yin to yang” test of imported cases?

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Recently, "physical-to-human" epidemics caused by cold chain foods have occurred in Shanghai Pudong, Qingdao in Shandong, Chengdu in Sichuan, Suifenhe in Heilongjiang and other places. In addition, in some areas, imported cases from overseas have frequently turned into positive cases. Even if a positive viral nucleic acid test has been recognized as the gold standard for the diagnosis of new coronavirus infections, once a "yin to yang" situation occurs, everyone will generally consider it to be the pot of nucleic acid test kits. Should nucleic acid detection reagents really carry this pot?


Since the beginning of the winter, the global epidemic has accelerated rapidly, and the pressure of "external defense input, internal defense rebound" is huge, scattered epidemics have occurred frequently, and "personal defense" imported from abroad has become the focus of my country's epidemic prevention and control. Imported cases "turn from negative to positive", there are many factors influencing nucleic acid testing! In the frequently-occurring imported cases, the problem is not entirely in the nucleic acid amplification test reagents. The main factors affecting the results of nucleic acid detection are as follows.



1. Viral load in the patient: The amount of virus replication in the human body has not yet reached a detectable level;

2. Sample quality factor: Does the sample collection meet the specification requirements? Are there enough virus cells in the collected specimens for nucleic acid detection;

3. The compatibility of virus transport media and detection reagents, whether the storage solution matrix will affect the quality of nucleic acid extraction and detection;

4. Nucleic acid extraction efficiency: the extraction efficiency of virus nucleic acid extraction reagents used is not high enough;

5. Sensitivity of detection reagents: The sensitivity of the virus nucleic acid detection reagents used is not high enough.


It can be seen that nucleic acid detection reagents and nucleic acid storage solutions are only one factor that affects nucleic acid detection. After removing this factor, there are many other factors that affect the results of nucleic acid detection. Many factors may lead to "false negative" results. The editor believes that there are three main reasons for the difference in nucleic acid test results under the current new situation.


One is the problem of sampling quality: improper selection of sampling site, insufficient sampling depth, and poor sample quality, leading to "false negative" results. Standardize the sampling process, strictly guarantee the sampling quality, and select the human endogenous internal standard COVID-19 detection kit, which can monitor whether the sampling is qualified and avoid "false negative" results caused by sampling.


The second is that the performance of the new crown nucleic acid detection reagents from different manufacturers is very different, and the differences in the detection results are justifiable. The "people with the same defense" input by the external defense should choose a more sensitive detection reagent. The higher the nucleic acid concentration, the higher the positive detection rate of nucleic acid detection. It is also related to the nucleic acid detection reagents, the selection of the primer probe design area, the stability of the reaction system, and the sensitivity of the detection reagents.


The third is that after the centralized procurement of new coronavirus nucleic acid amplification and detection reagents, sampling swabs, nucleic acid storage solutions, and nucleic acid extraction reagents are difficult to purchase together, and cannot be provided by the same manufacturer, and the whole process of detection cannot be guaranteed. The decision makers did not consider the differences in nucleic acid extraction technology, as well as the systemic errors caused by the influence of the material of the sampling swab and the matrix effect of virus transport media, because of the large application risk!


With the centralized procurement of domestic new crown detection reagents, more laboratories like to purchase inactivated nucleic acid preservation solutions. As a professional manufacturer of virus transport media, Desheng can not only guarantee the sampling quality and sampling effect, but also ensure the accuracy of the test results. Only by selecting nucleic acid detection reagents with higher sensitivity, and supporting systemic sampling swabs, nucleic acid storage solutions and extraction reagents, to ensure the systematicness of the detection system, can there be more reliable detection results.