The Confusion of the New Crown “Fuyang”: The Precision and Efficiency of Detection Technology

Since the outbreak of new coronary pneumonia, some discharged patients reviewed, the virus nucleic acid test results have become positive, referred to as “Fuyang”. The cause sparks of “Fuyang” cases and whether the “Fuyang” cases are contagious have aroused high public concern. On February 28, at a press conference held by the Joint Defense and Control Mechanism of the State Council, Guo Yanhong, the Ombudsman of the Medical, Political and Hospital Affairs Department of the National Health and Health Commission, said that no “Fuyang” cases had been detected to infect others.

Zhong Nanshan, head of the high-level expert group of the National Health and Reform Commission and a member of the Chinese Academy of Engineering, said earlier that it remains to be seen whether “Fuyang” patients can infect others again.

On March 5, Zhang Xiaochun, deputy director of the medical imaging department of Wuhan University Zhongnan Hospital, told the Beijing News that the increase in the phenomenon of “Fuyang” reflects the current dilemma of the accuracy and efficiency of the detection technology of new coronapneumonia, and also reflects the medical profession’s understanding of the new coronary pneumonia virus is still deepening the process, “this process is bound not to be easy.”

Zhang Suggested that when the conditions are ripe, multi-point nucleic acid testing, a variety of testing programs complement each other, from the discharge link and isolation period to stop the increase in “Fuyang” cases.

“Fuyang” dates back to February 14th.

The earliest case of “Fuyang” can be traced back to February 14, The couple in Ontario, Canada, two people in the hospital 14 days after the release of both “Fuyang.” They were discharged from hospital on 29 January and 31 January respectively and were clinically diagnosed as having recovered. But 14 days after being discharged from the hospital, both cases tested positive for nasopharyngeal swabs.

According to public reports from all over, since mid-to-late February 2020, the disease control departments of six provinces, including Guangdong, Jiangsu, Tianjin, Sichuan, Hunan and Hubei, have announced the contents of the “Fuyang” case notification. In addition, Canada, South Korea also found “Fuyang” cases.

On February 25, Song Tie, deputy director of the Guangdong Provincial Center for Disease Control and Prevention, said about 14% of patients discharged from hospital in Guangdong province were experiencing the phenomenon of “fuyang”. Li Yueping, director of the ICU at the Infection Center of the Eighth People’s Hospital in Guangzhou, said they found 13 cases of “Fuyang” patients during follow-up to the discharge cases.

On February 28, the Beijing News reporter learned from the Cdc of Xuzhou City, Jiangsu Province, on the 27th, the city has a case of discharge dispositive nucleic acid (asymptomatic). Three days before the retest positive, the case was released from quarantine and returned home.

On March 1, the Hainan provincial government’s official website reported that Hainan’s first case of “Fuyang” patients were discharged from the hospital again. At present, its body temperature has returned to normal for 5 days, pharynx swabs, fecal nucleic acid 2 consecutive times (interval of more than 24 hours) test are negative.

On February 27th, researchers at Zhongnan Hospital, Wuhan University, published a paper in the Journal of the American Medical Association, the world’s leading medical journal, to uncover a corner of the “Fuyang” phenomenon from a research perspective. The paper looked at four patients recovering from the new coronavirus, who tested positive for nucleic acid 5 to 13 days after being discharged from the hospital. All four were health care workers with mild to moderate severity and age ranges from 30 to 36 years old.

The paper showed that one of the patients had received two nucleic acid tests before discharge, the results were negative, AND CT showed that his lung lesions were significantly better absorbed, so he was discharged from the hospital. The patient was discharged from the hospital under strict home isolation and continued to take ostwere for nearly a month. In early February, the patient was re-examined before he was ready to return to work, and the CT results showed normal, but the first day of nucleic acid test results were weak positive, the next day the results of the review were positive.

The researchers concluded that current discharge standards, de-isolation standards and patient management issues may need to be reassessed.

On March 5, Xu Haibo, a professor of medical imaging at Wuhan University Zhongnan Hospital, one of the authors of the paper, told the Beijing News that no more effective method sits and standards have been found for how to adjust the discharge standard semen.

“We’re still in the study, there are no new results, and the results will be released in time. At present, according to the National Health and Reform Commission announced the implementation of the program is the best. Xu Haibo said.

“false negative” factors need to be excluded

In the “New Coronary Virus Pneumonia Prevention and Control Program (Sixth Edition)” issued by the National Health and Reform Commission, the new coronary pneumonia infection is mainly in patients with new coronavirus infection, asymptomatic infection may also become a source of infection. The “New Coronary Virus Pneumonia Prevention and Control Program (Fifth Edition)” shows that, in addition to the disappearance of clinical symptoms, the new coronavirus infection must be tested negative twice in a row for respiratory pathogen nucleic acid (at least 1 day between sampling intervals) before a cure can be determined to be discharged from the hospital; Factors that may produce false negatives need to be ruled out.

“false negative” becomes an important factor for patients to disrupt diagnosis before discharge or isolation. The new coronary pneumonia laboratory testing technical guide in the appendix to the New Coronary Virus Pneumonia Prevention and Control Program (Fifth Edition) has strict requirements for the types, methods, packaging and preservation of specimens, and problems in any one link may lead to “false negatives”.

Zhang Xiaochun to the Beijing News reporter, the current commonly used two nucleic acid detection methods for swabs, pharynx swab nucleic acid testing, the use of the reason is that they are efficient and convenient operation, suitable for the current situation with a large number of nucleic acid testing needs. However, the sampling limitations of both methods are greater: “The virus may not be in the pharynx and anus, in other body tissues. Coupled with the discharge of patients in the body of less virus, the operation may not be available, the actual sampletaken less. There are also kit sensitivity, patient physical differences and other interference factors, so it is easy to show ‘false negative’. “

“This is the contradiction between precision and efficiency. Zhang Xiaochun believes, “The number of people to be checked in the country is too large, to do a large-scale inspection, it is very difficult to take into account.” “

On February 18, Zhong Nanshan, a member of the Chinese Academy of Engineering, also said at a press conference that the diagnosis with nucleic acid testing was correct, but that if the sampling was inaccurate, it would cause a big difference in results.

According to the National Health and Reform Commission inspection center information, in the pharynx swab in the oral and nasal cavity sampling, because the new coronavirus is mainly in the deep part of the lungs, far away from the large trachea, infected people and more dry cough, sputum is not much, so the upper respiratory virus content is relatively low, increasing the probability of “false negative” appearance.

In Zhang Xiaochun’s view, nucleic acid detection can only give qualitative reference to infection, and CT imaging detection visually reflects the lung condition, to a certain extent, and nucleic acid detection complement each other. Zhang said that when the conditions gradually mature, “two-pronged” or even “multi-pronged”, with a variety of ways to make pre-hospital testing, I believe that can effectively reduce the subsequent “Fuyang” case increase.

The discharge standard in the seventh version of the consultation plan. Screenshot of the official website of the National Health and Care Commission

Some patients admitted to hospital and ruled out the possibility of reinfection with the virus

Guo Yanhong said at a press conference held by the State Council’s joint prevention and control mechanism on February 28 that the new coronal pneumonia virus is a new virus, its pathogenic mechanism, the full picture of the disease and the characteristics of the course need to be further deepened understanding.

Zhang Xiaochun told the Beijing News reporter, from the current clinical experience, the new coronary pneumonia virus can invade the human body many organs, so the virus may exist in the patient’s blood, feces, chest fluid and cerebrospinal fluid and other places, which for multi-point detection methods. Zhang Xiaochun believes that, in addition to the conventional pharynx swab, swab test, should be combined with the patient’s clinical symptoms to determine nucleic acid testing points, which is conducive to preventing sampling is not allowed, sample size is not enough, sampling site virus content can not reflect the overall problem. However, as with a variety of testing, a wide range of multi-point nucleic acid testing, each time the required detection time will be more.

Subject to the detection needs of the new coronavirus itself research progress, the current measures taken by the “Fuyang” phenomenon is more limited. Public information from the disease control departments around the country shows that all areas are still strengthening follow-up to discharged patients, strengthening health monitoring and other follow-up intervention stoics.

For Hainan’s “Fuyang” case again discharged from the experience, Hainan Provincial People’s Hospital, the head of the disease control office, deputy director of the infection department Wu Wei introduced, “Fuyang” patients again after hospitalization examination found that the patient’s body has produced IgG antibodies, while IgM has been negative, ruled out the possibility of reinfection with the virus. Hainan Provincial People’s Hospital will carry out nucleic acid tests of whole blood and feces before patients who meet the criteria of the National Health and Health Commission are discharged from the hospital, and will be cleared of full negative. The hospital will strengthen follow-up to patients discharged from the new coronary pneumonia, and implement 14 days of free rehabilitation isolation and medical observation at designated places of the National Centerfor Disease Control.

From the day the patient is discharged to 12 weeks after discharge, a review node for the discharged patient sits in the fourth week, week 8 and week 12 shall be set up. Focus on reviewing blood routine, blood biochemistry, finger oxygen, new coronavirus antibodies, multi-site nucleic acid, chest CT and other items, health guidance and health monitoring, to achieve the whole process management.

On the morning of February 22nd, Zhang Fuchun, deputy secretary and chief physician of the 8th People’s Hospital of Guangzhou, suggested at the press conference that discharged patients should still be kept in isolation at home and meal-sharing system at home. According to it, some patients after two weeks out of the hospital after positive, the current period of illness and the time of poisoning is not clear, so all patients are required to return to the hospital after two weeks, four weeks after follow-up.

In addition to strict follow-up mechanism, Zhang Xiaochun, deputy director of medical imaging department at Zhongnan Hospital, Wuhan University, believes that it is possible to consider extending community isolation and home isolation time for discharged patients. “Rehabilitation persons also need to be isolated in the community for 14 days after being released from hospital isolation, during which time they can receive simple medical care. This time may be considered to extend to 2 months, or even 3 months, to lengthe the observation of the time window. Zhang Xiaochun suggested.

On March 4, the Seventh edition of the medical treatment plan published by the National Health and Reform Commission was revised after discharge. In view of the fact that a small number of discharged patients have tested positive for nucleic acid, in order to enhance the health management and isolation of discharged patients, replace the words “14 days of self-health monitoring” with the words “14 days of isolation management and health monitoring should continue”. This means that after discharge, patients are still required to undergo health monitoring by health care providers, which is more rigorous than previous self-testing.

Whether or not the patient sins of “Fuyang” is infected is uncertain

Because “Fuyang” cases are found in the re-examination after the lifting of isolation, so the free movement of “Fuyang” cases whether it is contagious, become the “Fuyang” at present the most attention points.

Guo Yanhong, Ombudsman of the Medical And Political Hospital Authority of the National Health and Reform Commission, introduced the situation of Fuyang. CCTV News Screenshot

The infectious understanding of the current case of Fuyang, as well as the current global medical community’s understanding of the new coronavirus, is still under exploration.

Vanessa Allen, head of medical microbiology at the Ontario Provincial Department of Health, said in a press release that some genetic or viral residues were found in the samples of the Fuyang case, but that the virus’s survival status could not be determined from those residues, nor was it clear. “Whether the patient is still contagious.

On February 27, Zhong Nanshan said that new coronary pneumonia is a new infectious disease, do not know its transmission process, at present can not be absolutely conclusive. But according to the microbe rules, as long as the patient’s body produces enough antibodies, the patient will no longer be infected. But it remains to be seen how such patients will no longer be infected.

In Xu Haibo’s view, the nucleic acid test for the recovered discharge case is positive, which may indicate that some of the recovering people still carry the virus, but whether it is contagious is still unclear.

Zhang Xiaochun believes that “Fuyang” may be due to the case discharge to be tested when the body virus volume is low, did not reach the nucleic acid test positive degree, so it was not detected; This shows that the patient in the isolation period, the virus in the body is still a certain activity, so it is very necessary to prevent “fuyang” case stoic infectious.

Wu Wei, head of the disease control office of Hainan Provincial People’s Hospital and deputy director of the infection department, believes that patients discharged after meeting the national discharge standard are theoretically in the process of rehabilitation and the body stock virus is in the process of removal. If a recovery nucleic acid test is positive, as long as the clinical comprehensive judgment is not a recurrence of the disease, it will not pose a great threat, the possibility of becoming a new source of infection is very small.

On February 25, Li Yueping, director of the ICU of the Infection Center of the Eighth People’s Hospital in Guangzhou, also introduced at the outbreak conference in Guangdong Province, although the nucleic acid test for the “Fuyang” case was positive, it was technically difficult to distinguish between live and dead viruses. Therefore, for the prevention and control of viruses, still need to be strictly guarded.

“On the phenomenon of ‘Fuyang’, hospitals and individuals should pay attention to prevention and control, but also do not need to panic too much, not to discriminate against patients who have been discharged from the hospital. Zhang said, “We have a way to deal with, but at all levels need to do a good trade-off, there is a lot of room for improvement.” “