What is the Novel Coronavirus test kit? How do we detect novel Coronavirus?   

The Novel Coronavirus test kits currently used in medical institutions are mainly divided into two nucleic acid test kits and antibody test kits   

What is a nucleic acid test kit?   

Nucleic acid detection is to diagnose the virus by detecting the genetic material nucleic acid of the virus. RNA reverse transcription reaction and PCR technology are adopted. In short, it is to use biotechnology to capture the unique nucleic acid gene fragments of the Novel Coronavirus and then replicate them in large quantities to amplify their characteristics infinitely. Nucleic acid detection kit design is aimed at will be coronavirus specific gene fragments, and also made specific validation, use kit to detect other similar viruses such as SARS, influenza virus, test results are negative, only test will be when the coronavirus is positive, this ensures that the specificity of the kit, and not the misdiagnosis.   

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Why does nucleic acid test kit miss detection?   

You have seen the phenomenon of missing nucleic acid detection in the news. Why is this? First, we do not have a good understanding of the Novel Coronavirus. The process of infection and the progress of the disease are not clear at present, which may lead to inappropriate sampling time and thus missed detection. Second, everyone's immune resistance is different, and they are also infected with the virus, but some people can quickly remove the virus, and the amount of virus in the body is small, so it is not easy to detect naturally. Third, the kit has its own sensitivity limits, that is to say, the amount of virus in the sample is small to a certain extent, and the kit cannot detect it, which is the limitation of nucleic acid detection technology. In addition, whether the sample collection is standardized, whether the transport and storage are appropriate and other factors will affect the positive detection rate of the kit.   

The existence of missing detection cannot simply be attributed to the nucleic acid kit, it is caused by a combination of factors. Therefore, kit test results are only for clinical reference, not the only standard for clinical diagnosis, but also need to be combined with the clinical manifestations of patients and other laboratory tests for comprehensive analysis of the disease.   

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What is an antibody test kit?   

The antibody test kit is a test that indicates the possibility of novel Coronavirus infection by detecting novel Coronavirus specific antibodies. Incubation period of the virus invades the body, after a certain antibodies, first is immunoglobulin M (IgM), maintaining time is short, but the antibody concentration is low, for a few days to several weeks in the blood, is the diagnostic index of acute infection, immunoglobulin G (IgG) appear a little slower, IgM in near disappears, IgG levels to peak, High concentration of IgG after production and long maintenance time, IgG positive indicates the presence of middle and late infection or previous infection. Therefore, the presence and content of specific antibodies IgM and IgG in blood samples can be used to indirectly determine the presence and infection of viruses in the body.   

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How to detect novel Coronavirus specific antibodies in samples?   

In the detection of blood samples, the use of synthetic antigen, through the specific antibody in the sample of antigen antibody binding reaction and converted into visual signal to determine. Current, approved will be coronavirus antibody detection kit with colloidal gold method and magnetic particles chemiluminescence method, colloidal gold method results will form a visible banding, short detection time, generally about 15 minutes can out as a result, the magnetic particles chemiluminescence method through the reaction process of optical signal detection, sensitivity is higher than the colloidal gold method, test process typically take half an hour.   

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Limitations of antibody testing kits   

According to the general rule of immune response, the generation and disappearance of antibodies is a dynamic process. If the sampling time is too early, antibodies have not been produced or the production amount is low, it will cause missed detection. Therefore, the current approved Novel Coronavirus antibody test is intended to be used only as a supplementary test indicator for suspected cases of novel Coronavirus nucleic acid negative test or in conjunction with nucleic acid test in the diagnosis of suspected cases, and cannot be used as a basis for the diagnosis and exclusion of pneumonia in novel Coronavirus infection.   

Generally speaking, nucleic acid detection is the preferred method for novel Coronavirus detection, which has the characteristics of early diagnosis, high sensitivity and specificity. Antibody detection, on the other hand, can be used as a supplementary means for nucleic acid diagnosis due to its convenience and rapid detection. Nucleic acid test proves whether the human body is infected by the virus from the pathological point of view, antibody test from the serological point of view side evidence, the combination of the two, coupled with clinical indications, can more comprehensively reflect the real state of the infected object, but also more conducive to the adoption of corresponding measures.