Patients who have recovered from the new coronavirus pneumonia have turned to a positive nucleic acid test in some places. Although a positive result does not equal relapse, such information has also caused some panic to the public and may increase the cost of prevention and control.
This panic is expected to be eased by scientific research.
On March 14, 2020, the Qinchuan team of the Institute of Medical Animal Experiments of the Chinese Academy of Medical Sciences published a non-peer-reviewed study entitled "Reinfection could not occur in SARS-CoV-2 infected rhesus macaques" on the preprinted version of the platform bioRxiv.
In this study, the symptoms of disappearance of monkeys infected with the new coronavirus were re-exposed longitudinally.
Researchers found that when first infected with the new coronavirus, weight loss occurred in some monkeys, the virus replicated mainly in the nose, throat, lungs, and intestines, and moderate interstitiality appeared on day 7 (dpi) after infection pneumonia.
After monkey symptoms resolved and specific antibodies were positive, half of infected monkeys were challenged with the same dose of SARS-CoV-2 strain.
It is worth noting that no viral load was found in nasopharyngeal and anal swabs along the time axis in re-exposed monkeys, and no virus replication was found in all major tissue segments of reinfection (dpr).
Combining subsequent virological, radiological, and pathological findings, re-exposed monkeys did not relapse with new coronavirus pneumonia.
The results of this study indicate that primary SARS-CoV-2 infection can prevent subsequent exposure, which is of great significance for the prognosis and vaccine design of new coronavirus pneumonia diseases.
Although the study object was monkeys, it may also be an important research finding for more than 80,000 patients diagnosed in 31 provinces, autonomous regions, and municipalities.
Previously, due to insufficient scientific research, the problem of positive detection of discharged patients increased the cost and difficulty of prevention and control to a certain extent.
On March 4th, due to concerns about the detection of discharged patients becoming positive, Wuhan Jiang'an Fangcai Hospital issued an "Emergency Notice" saying that according to the latest notification from the Municipal Epidemic Prevention Command, there were more relapsed patients recently discharged. , Causing the patient to be re-admitted to hospital for treatment.
In order to reduce the recurrence of the disease and ensure that everyone is completely cured to achieve the goal of "zero turnaround", the hospital decided to conduct a blood test on all patients who are going to be discharged from the cabin and perform virus antibodies Ig-M and Ig-G on the same day to ensure that the patients are fully recovered. Discharged, please all patients to cooperate. The inspections will begin on March 5.
Earlier, several experts also told Yicai.com that a positive result does not equal relapse.
"There is no recurrence at present. Some are not good yet, some are better, and the nucleic acid has not completely disappeared (not necessarily a live virus), but sometimes it is absent at the time of examination." A front-line clinical expert said.
In addition, the accuracy of nucleic acid detection depends not only on the sensitivity and specificity of the diagnostic reagent itself, but also on the standardization of the sampling staff and the amount of virus in the patient.
"Sometimes virus samples can be taken in the throat of patients, sometimes they can't be taken, so there will be some so-called nucleic acid negative patients. Secondly, when the sampling is not performed properly, the virus samples will not be taken, and false negatives will appear. However, for patients in the recovery phase, treatment may not be necessary even if the nucleic acid is positive, "said the clinical expert.
An immunology expert also said that once the virus is infected, antibodies are produced in the body. This antibody has a protective effect on the human body and the elimination of the virus will continue.
At present, nucleic acid positives detected from the body are not necessarily live viruses, and the virus fragments will be slowly cleared in patients with prognosis.
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