Is domestic nucleic acid testing accurate?

Novel Coronavirus is like a strange ghost. The ferocity of the early stage of the epidemic, the "re-positive" in the middle stage and the "asymptomatic" in the late stage have always been unpredictable.

Viral nucleic acid test is an important basis for the diagnosis and exclusion of novel coronavirus infection.

But why do some COVID-19 patients have to undergo multiple tests before they are confirmed positive? It was reported that the case of Ziyang 4 in Sichuan was confirmed after 9 nucleic acid tests.

Why do some COVID-19 patients have "repositive" symptoms after treatment? In fact, a large number of patients were false "repositive" and true "false Yin", and the patients were "false negative" caused by nucleic acid test errors. The virus in their bodies was not cleared, but the nucleic acid test was not detected before discharge.

Why does it take multiple tests to find positive? Why does the patient recover after being cured and discharged from hospital?

Nucleic acid test mainly collected pharyngeal swabs, novel coronavirus mainly located in lung, trachea, bronchus and other parts of the lower respiratory tract, while nasopharynx and oropharynx in the upper respiratory tract. Come on inchoate upper respiratory tract has a few virus, late is less, pharyngeal ministry may have virus residue, but can not be collected necessarily.

Nucleic acid tests require a minimum amount of virus to detect, and there is more virus in the lower respiratory tract than in the upper respiratory tract, so samples taken from the upper respiratory tract can be false negative no matter how many times they are tested.

"Repositive" may also be a virus fragment or dead virus detected in the body, which does not mean that the patient has not been cured or the condition has repeated.

"Repositive" may also be an intermittent detoxification of the patient. At the end of the disease, the virus level is low and the patient is likely to have no symptoms such as coughing or sneezing. From the current observation of the situation, repositive patients, there have been no reported cases of infection.

For novel coronavirusIgM positive patients, nucleic acid examination and chest CT should be conducted. If there is any abnormality, they should be admitted to hospital. If there is no abnormality, they should be quarantined until the nucleic acid test of different sites is negative for three times and the IgG value is greater than 4 times of IgM value, and the isolation can be released.

In case of false-negative nucleic acid test, the discharge criteria for COVID-19 patients should be strictly implemented. In addition to the complete absorption of acute inflammation and negative nucleic acid tests for two throat swabs, patients can be tested for anal swabs and be discharged after three negative nucleic acid tests.

Of course, current data and studies show that patients with COVID-19 are not likely to develop COVID-19 again after being discharged from hospital, and the possibility of transmission is not high. Do not discriminate against them.

However, the public should still pay attention to personal protection, not to be careless, wear masks, wash hands frequently, avoid gatherings, and keep a distance.