China News Service, May 23. Guo Yanhong, an inspector of the National Health and Medical Commission's Medical Administration and Hospital Administration Bureau, said on the 23rd that although the specificity of nucleic acid detection is 100%, in actual work, the laboratory may be caused by the test process and operation. of some contamination resulting in false positives.

In addition, there are individual laboratories including technicians who do not strictly follow the prescribed work procedures, which will also cause false positive results.

  The State Council's joint prevention and control mechanism held a press conference on the 23rd.

At the meeting, a reporter asked: There have been many cases of nucleic acid false positives recently. Why did this happen?

Does this mean that the sensitivity of existing nucleic acid tests for the Ormicon strain has decreased?

  Guo Yanhong responded that nucleic acid detection is a very professional technology. In recent years, it has received high attention from the public, and has gradually approached ordinary people.

For nucleic acid detection, it is the gold standard for diagnosing new coronavirus infection. Its positive detection time is early and the accuracy is high. It is an internationally recognized detection technology for mature pathogens. The use of nucleic acid detection can detect infected people as soon as possible and lock the infection. The scope of the epidemic has played a key role in the "outpost" of the epidemic prevention and control work. Through nucleic acid testing, prevention and control measures can be taken to cut off the transmission route. For the implementation of the "Four Early Mornings", the "external defense import, internal defense rebound" and The general policy of "dynamic clearing" plays a very important role.

  According to experts, although the specificity of nucleic acid detection is 100%, in actual work, the laboratory may cause false positives due to some contamination caused by the test process and operation. It is divided into two aspects. On the one hand, it is the legacy contamination of amplification products. In the process of large-scale nucleic acid detection, due to the large sample size and the continuous working method of “stopping people without stopping”, each round of amplification is required. Cleaning between incremental tests may not be in place.

At the same time, there is no guarantee that each amplification tube is airtight, which may cause false positives.

In addition, cross-contamination may occur between samples during the testing process, such as positive samples or the use of quality controls that contaminate samples that were originally negative.

After it is made, it is a false positive due to cross-contamination.

  In addition, there are individual laboratories including technicians who do not strictly follow the prescribed work procedures, which will also cause false positive results.

None of these situations actually means that the sensitivity of nucleic acid testing to the Omicron strain has decreased.

Nucleic acid detection is still a key technical means to detect the new coronavirus.

  Guo Yanhong pointed out that in order to avoid "false positives" to the greatest extent, all testing institutions are required to further implement the requirements of technical guidelines and work procedures for nucleic acid testing, especially to do a good job in quality control management, including indoor quality control and inter-quality control. In quality assessment, especially for some links that are prone to problems, it is necessary to strengthen the implementation of work requirements and measures, especially to strictly implement the cleaning and disinfection of the laboratory environment to reduce the possibility of laboratory contamination.

When there is an abnormal increase in positive results in the laboratory, it is necessary to carefully sort out the workflow and analyze the possible reasons, especially to exclude the possibility of false positives caused by operation or laboratory contamination.

And strengthen the frequency of disinfection and cleaning of environmental equipment and work surfaces to minimize laboratory contamination.

  In addition, it is required to reasonably arrange the shifts of the staff to avoid excessive fatigue, which can easily lead to omissions in the work process, and to maximize the quality.

In addition, on the basis of strengthening the inter-laboratory quality assessment work, the supervision and inspection of nucleic acid testing institutions has been further strengthened, with special emphasis on practicing according to the law and strictly testing the quality.

For violations of laws and regulations, we must resolutely investigate and punish them, and report them nationwide.

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