China-Singapore Jingwei, May 16 (Wang Yuling) After receiving a positive nucleic acid test report, the review in the hospital showed "negative" again.

This is what happened to residents of some communities in Huangpu District, Shanghai. The medical institution that conducted nucleic acid testing for them, Runda Medical, was also pushed to the forefront.

Runda Medical stated in its answer to the inquiry letter from the Shanghai Stock Exchange that it has asked the Chinese Science Laboratory to start an internal self-examination on the relevant situation and cooperate with the relevant departments in the investigation.

  Sino-Singapore Jingwei noticed that not only Runda Medical was involved in the "false positive" rumors, but Hehe Diagnostics and Shanghai Junji Medical Laboratory were also involved in the "false positive" controversy.

  So, from the current public information, what are the doubts about Runda Medical's "false positive" controversy?

Whether it's "false positives" or "positive false positives," who is to blame?

What causes "false positives"?

  "The specificity of nucleic acid testing is 100% in methodology, that is, nucleic acid testing has no false positives in methodology. Therefore, nucleic acid testing has always been the basis for determining new crown infection, and it is the 'gold standard'." National Health Commission Clinical Laboratory Center Deputy director Li Jinming once said in public.

  The marketing manager of a company that produces rapid nucleic acid detection reagents for new crowns also expressed a similar view to Sino-Singapore Jingwei. He said that starting from the principle of nucleic acid detection kits, the selection of pathogen targets needs to be specific. Or multiple specific gene sequences are used as targets, and corresponding primer probes are designed, that is, "one key opens one lock", which is not prone to "false positives".

  However, in recent days, many nucleic acid testing institutions have fallen into the question of "false positives".

  In addition to Runda Medical, Hehe Diagnostics was previously notified by the Hefei Epidemic Prevention and Control Emergency Headquarters to warn and suspend cooperation.

According to a report by China News Weekly, on May 7, a resident of Baoshan District, Shanghai said that his mother-in-law tested positive for nucleic acid. On the morning of the 8th, he was transferred to a cabin without retesting the nucleic acid and the antigen was negative.

On the afternoon of the 9th, the report was changed to negative, and the test result in the cabin that day was also negative.

It is reported that the institution responsible for testing is Shanghai Junji Medical Laboratory.

  However, the person in charge of the Shanghai Clinical Laboratory Quality Control Center recently responded to an exclusive interview with the media, saying that experts have been specially organized to conduct medical inspection experiments on Huada, Dean, Zhongke Runda, Lanwei, Jinyu, Junji, and Nuclear Huaxi. The laboratory has carried out more than 20 special inspections to supervise the qualifications of testing institutions and personnel, sample acceptance, testing procedures, result interpretation, result reporting, and laboratory pollution prevention. The results are recorded and backtracked to determine whether the test results are reliable.

So far, more than 4,700 on-site supervision and inspections have been carried out.

The results of quality monitoring show that the overall testing situation of the city's medical testing laboratories is standardized and no quality problems have been found.

  So, what led to the emergence of the "false positive" controversy?

Dr. Liu from the laboratory department of a tertiary hospital in Wuhan analyzed Sino-Singapore Jingwei that if the testing process of nucleic acid testing is divided into pre-testing, testing and post-testing, each process will put forward operational challenges for institutions and personnel engaged in nucleic acid testing. There is a risk of "false positives".

  In the eyes of industry insiders, contamination may be the primary cause of "false positives".

The People's Government of Shangcheng District, Hangzhou City has previously released the causes of contamination in nucleic acid testing laboratories, which stated that in the process of nucleic acid testing of the new coronavirus, the following types of contamination are common: contamination of amplified fragments (product contamination), contamination of natural genomic DNA , reagent contamination (storage or working fluid), and cross-contamination between samples.

  According to public information, the most likely form of PCR product contamination is aerosol contamination, which requires very high requirements for the closed disinfecting ability of the gas membrane structure laboratory.

Sino-Singapore Jingwei noticed that Zhongke Runda opened the air-film structure laboratory in early May, and completed the testing of 20,000 tubes on the day of launch. At the same time, the initial design capacity of the air-film laboratory was 100,000 tubes per day.

  A staff member who participated in the construction of the air chamber laboratory introduced to Sino-Singapore Jingwei that the air-membrane structure buildings are generally only used for gymnasiums or occasions where dust needs to be sealed, and they were not applied to emergency medical buildings until the epidemic period.

As for whether the laboratories with air-film structures on the market can effectively prevent contamination, he commented: "The good and the bad are mixed."

  "The air membrane structure laboratory should be divided into reagent preparation area, sample pre-processing area, amplification analysis area, sample processing area, and equipment such as automatic spotting instrument and automatic nucleic acid extraction instrument according to the daily detection volume of nucleic acid detection. Referring to the standard specifications of clean workshops, in order to avoid pollution, the air membrane structure laboratory should be equipped with a fresh air ventilation system, with a ventilation frequency of more than 15 times per hour, to filter indoor biological aerosols. However, some of the air membrane structure experiments circulating on the market should be The room is not up to standard," the staff member said.

  "It takes about two weeks for us to build a standardized air-membrane structure laboratory, but now the construction time of the air-membrane structure laboratory on the market is very tight, and some are only a few days, and can only be used for short-term use." The staff said.

  Sino-Singapore Jingwei noticed that there are many units on the market that can undertake air-membrane structure laboratories, including Tongfang Renhuan, Shanyi, Xinyuan, etc. Some of these companies claim on their official websites that all indicators meet or exceed the P2 biosafety laboratory Require.

However, Sino-Singapore Jingwei noticed that the national standard "General Technical Requirements for Inflatable Membrane Structure Clean Laboratory" is still being drafted.

  Secondly, people in the industry believe that the different standards of different varieties of detection reagents may be another major cause of "false positives".

  According to the "Technical Guidelines for Laboratory Testing of Pneumonia Infected by Novel Coronavirus (Seventh Edition)" (hereinafter referred to as the Guidelines), no Ct value or Ct=40 is defined as negative, and Ct value less than 37 can be reported as positive.

While the Ct value is between 37-40, the guidelines recommend repeating the experiment, which also states that if a commercial kit is used, the instructions provided by the manufacturer shall prevail.

  The market manager of a new crown nucleic acid detection reagent company analyzed Sino-Singapore Jingwei that different detection reagents have different determinations of positive standards, and there may be a positive result for one reagent and a negative result for the other.

As far as Zhongke Runda is concerned, it uses two kinds of reagents, "Side Di" reagent and "Berjie" reagent, the former is an ultra-fast PCR detection reagent.

  "The so-called rapid detection reagents for new crown nucleic acid include point-of-care detection (POCT) molecular diagnostic technology based on isothermal amplification technology, and kits based on rapid PCR technology. Rapid detection reagents are mainly used in fever clinics and other emergency scenarios that require rapid reporting. The report can be issued within 1 hour at the earliest, the operation is simple, and the reagent sensitivity is high," the person said.

  However, he also emphasized that the risk of "false positives" for rapid detection reagents is slightly higher than that of conventional PCR reagents, especially for rapid detection products based on rapid PCR technology, to complete so many amplification cycles in a short period of time, it is possible to improve " false positive" probability.

At the same time, there is also the risk of aerosol contamination during operation.

  Finally, receiving excessive sample volume or leading to untimely sample detection, etc., may also produce "false positives".

According to the sealed document "Zhongke Runda's Statement on the Test Results of 5 Samples in Wuliqiao" previously circulated on the Internet, it stated that on May 7, 2022, the Zhongke Runda Medical Laboratory received Luban Road Lane 388 Five samples were screened at the sampling point. The sampling time was between 8:43 and 9:55 on May 7, the receiving time was 14:50 on May 7, and the report upload time was 4:44 on May 8.

  That is to say, if the above "Statement of the Situation is true", the time from sampling to receiving the sample should be at least five hours apart.

According to the "Regional Novel Coronavirus Nucleic Acid Detection Organization Implementation Guidelines (Third Edition)" by the Joint Prevention and Control Mechanism Comprehensive Group of the State Council, samples should be delivered to the laboratory within 3 hours after collection at the latest.

At the same time, the number of samples sent each time is about 10% of the testing agency's single-day testing capacity.

Does Runda Medical have the problem of untimely submission for inspection due to over-sample reception?

Sino-Singapore Jingwei has called Runda Medical many times and still has not been connected.

Are nucleic acid testing institutions liable?

  Sino-Singapore Jingwei noted that since the outbreak of the new crown epidemic, a number of third-party medical testing institutions have been notified of problems with nucleic acid testing institutions, and more than one has been subject to public pressure and regulatory penalties due to the "false positive" problem.

  So, should nucleic acid testing institutions take responsibility for this?

In this regard, Professor Deng Yong from the Law Department of Beijing University of Traditional Chinese Medicine analyzed Sino-Singapore Jingwei that firstly, it is necessary to distinguish between "false positives" and "positive frauds".

  "PCR detection technology is recognized as the 'gold standard' for new coronavirus testing at home and abroad, but in practice there are many factors that ultimately affect the results of the report, and there are certain difficulties in how to accurately identify these reasons and implement the legal responsibility of relevant subjects. From the current Judging from the relevant notification from the Ministry of Commerce, most of the regions only issued a warning and suspended cooperation to the laboratories involved, and did not further investigate the legal responsibility of the laboratories." Deng Yong said.

  Specifically, Deng Yong refined it into civil liability, administrative liability, and criminal liability.

In terms of civil liability, if some patients are forced to go to makeshift hospitals or quarantine at home because of "false positive" reports, can they apply for compensation to the testing agency?

  Deng Yong explained that in terms of tort liability, although there is a possibility that the quarantined person suffers losses due to the wrong report issued by the inspection party, it is difficult for the inspection agency to meet the "intentional" requirement from the point of view of the establishment of liability, because The testing party has no subjective motivation to "deliberately issue false positive reports to cause losses to others", but it may seem far-fetched to explain from the perspective of consumables selection, kit selection, and laboratory standardization.

And in the same way, under the current epidemic prevention situation, it is difficult to prove the degree of loss suffered by the quarantined.

  From the perspective of administrative responsibility, Deng Yong said that "issuing a wrong test report" is not enough to lead to administrative punishment, and the basis for punishing the inspector is more "failure to collect pathogenic microorganism samples in accordance with regulations" "failure to comply with laboratory The inspection party will only be held accountable when the inspection is distorted due to reasons such as biosafety technical specifications and operating procedures.

  From the perspective of criminal responsibility, Deng Yong said that Article 229 of the Criminal Law stipulates the "crime of providing false certification documents" and "the crime of issuing major inaccurate certification documents". Possibility of sin-eligible subjects.

However, the requirements of criminal responsibility are stricter, and generally need to meet the prosecution standards. After this issue, it should be considered that only "false positives" have intentional behavior, and "sample contamination" should be treated as negligence. As for "inaccurate test results" ", it should not be deemed that it meets the subjective requirements of the relevant crime.

How to deal with "false positives"?

  On May 13, Guo Yanhong, the supervisory commissioner of the National Health and Medical Commission's Medical Administration and Medical Administration Bureau, said at a press conference of the State Council's Joint Prevention and Control Mechanism that establishing a 15-minute walk for nucleic acid testing "sampling circles" in big cities will, on the one hand, help the public to visit nearby places. It is easier to accept nucleic acid testing services, and at the same time, it is more conducive to the early detection of infected people, to improve the sensitivity of detection and early warning, and to detect the epidemic early, which is conducive to the timely control of the epidemic.

  According to the industry weekly report of Shanghai Securities on May 9, Beijing, Shanghai, Hangzhou, Ningbo and other places have successively introduced nucleic acid testing requirements, and increased the construction of normalized nucleic acid testing points. Among them, 10,000 free nucleic acid sampling points have been set up in Hangzhou area. Citizens are required to test nucleic acid every 48 hours.

According to the population of Hangzhou, about 1,200 people correspond to one testing point.

According to this ratio, only considering the urban population, at least 750,000 new testing points will be added nationwide.

  Yu Chuanhua, a professor of epidemiology and health statistics at Wuhan University, analyzed Sino-Singapore Jingwei, "According to Bayes' theorem, if a test is not 100% accurate, there may be "false negatives" (missed diagnoses) or "false negatives". Positive” (misdiagnosed). The positive predictive value refers to the proportion of the truly “disease” cases (true positives) among all the positive cases detected by the screening test, reflecting the target disease for those with positive screening test results It is closely related to the infection rate. When the infection rate is high, the positive predictive value is larger. That is, correspondingly, the positive predictive value is lower when the infection rate is low. That is, the lower the infection rate is. The probability of the occurrence of "false positives" will be greater."

  That is, the larger the population, the lower the infection rate, and it is difficult to avoid "false positives".

According to a paper published in "Shanghai Preventive Medicine" by the School of Public Health of Fudan University, when the population is large and the infection rate is low, the use of screening tests for large-scale population screening not only increases specificity, but also results in a large number of "false positives". The resulting problems cannot be ignored.

  How to deal with "false positives"?

Yu Chuanhua said that there should be a certain degree of patience and fault tolerance for "false positives". "From a scientific point of view, this may happen." Yu Chuanhua said.

  In addition, Sino-Singapore Jingwei noted that local CDCs are carrying out the review and reporting of local suspected positive specimens, the identification of Omicron strains, vaccine strains, etc., and the urgent review of difficult specimens.

  At the same time, the "Regional Novel Coronavirus Nucleic Acid Testing Organization Implementation Guidelines (Third Edition)" stated that disposal procedures were set up for both positive apheresis tests and positive mixed collection tests.

First, the testing agency should immediately report to the data statistics special class of the nucleic acid testing working group. The apheresis will not be reviewed. The mixed sampling requires the working group to simultaneously notify the emergency sampling team, the community (community) where the mixed sample is located, and the public security organ, and immediately isolate the center in place. involved personnel and conduct apheresis review.

  But how are the standards for review established?

How is the CDC responding?

This series of issues remains to be further clarified.

  Virologist Chang Rongshan told Sino-Singapore Jingwei that according to the three principles of infectious disease prevention and control, the first is to isolate the source of infection, the second is to isolate the transmission route, and the third is to protect the susceptible population.

Based on this, the role of sentinel points such as pharmacies and fever clinics should be brought into play, and people should be encouraged to take the initiative to test and be the first responsible person for their own health.

(Sino-Singapore Jingwei APP)

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Responsible editor: Li Zhongyuan

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