Nucleic acid detection is an important diagnostic standard for new crown pneumonia. Wuhan recently proposed the hard core task: accelerating the progress of nucleic acid detection. As of June 6, more than 43000 samples have been tested in Wuhan.
Many medical staff and cadres interviewed by Xinhua view said that time is tight and task is heavy, and efforts need to be redoubled to complete the goal of comprehensive testing.
How is the test progress?
According to the survey, in the basic communities of Wuhan, the progress of the two-day test was generally significantly accelerated.
In some communities, all suspected patients have completed the preliminary examination, and some patients with negative test results have been reexamined and are waiting for the reexamination results. Dai Mingxia, Secretary of Jilin community, Yongqing street, Jiangan District, Wuhan City, introduced that the last suspected patient in the community had completed preliminary sampling on June 6, and all 30 suspected cases had been tested for nucleic acid. If the result of the initial examination is negative, it shall be tested again; if the result is positive, it shall be sent to a doctor directly.
However, some communities still have some stocks of suspected patients without nucleic acid testing.
According to the director of a community in the main urban area, there are 8 suspected patients registered in the community, but only one person can be arranged for nucleic acid test every day. In another community in the main urban area, there are currently 18 suspected patients, 4 of whom will be sent to the health service center for sampling and testing on the 7th.
According to the person in charge of a main urban area, as of June 6, there were more than 700 suspected patients in the whole area, more than 170 nucleic acids were detected on May 5, more than 300 on June 6, and it will take two days to complete all the detection tasks. Due to the heavy task of nucleic acid detection, the suspected patients with mild disease whose first test result is negative will not be reexamined temporarily, and will go home for isolation first. The person in charge said.
It is worth noting that although the detection technology has been gradually improved and the detection progress is accelerating, the willingness of nucleic acid detection of some suspected patients is not high. The reporter interviewed a confirmed patient named Zhang who was admitted to the hospital. His son and daughter-in-law were infected with fever, lung infection and other suspected symptoms. But for more than ten days, the son and daughter-in-law have not registered for nucleic acid testing. They said the symptoms were mild, they had been taking injections and drugs in the hospital, and the tests were useless. Anyway, there was no specific medicine.
Are reagents and sampling personnel sufficient?
At present, Wuhan has 35 relevant institutions to carry out nucleic acid detection, and the single day sample detection capacity has increased from 200 in the early stage of the outbreak to thousands in the near future.
According to the relevant person in charge of Wuhan health and Health Commission, there are about 109000 test reagents in stock in Wuhan, and more than 7000 samples can be tested every day. The testing capacity of various testing institutions has been able to meet the needs of clinical testing.
According to the reporters investigation, there are still some problems affecting the rapid and full development of detection.
First of all, there is a shortage of front-line sampling personnel, who are not proficient in temporary work. Li Yirong, director of the laboratory of Central South Hospital of Wuhan University, said that at present, the collected samples are mainly throat swabs, which requires standardized training and rich experience of the collection personnel, so as to efficiently collect the cells infected by the virus.
According to a person in charge of the main urban area of Wuhan City, sampling personnel are in short supply, most of them are on duty through temporary training, and their early proficiency is not enough, which affects the progress of testing. As the samples can not be submitted for inspection for more than 2-3 hours at room temperature, in order to ensure the time window, the original 300 test targets of a batch every day can only be completed for each batch of 670.
Secondly, the reporter found that the load between the agencies is uneven, and the actual detection capacity of some agencies is far lower than the detection capacity.
As one of the 35 nucleic acid testing institutions, Huada gene has a capacity of more than 5000 cases per day in Wuhan. However, on February 5, the actual detection amount of Huada gene in Wuhan was only 463. According to the analysis of the relevant person in charge of BGI, this may be that some samples were detained in the hospital and were not sent to the third-party testing agency in time.
In addition, some detection links take time. After receiving the reagents in the early morning of January 21, the laboratory medical center of the peoples Hospital of Wuhan University officially carried out the nucleic acid detection of suspected cases. More than 1000 samples were detected in the past two days, and 8861 samples had been detected by 16:00 on the 6th.
Li Yan, director of the laboratory of the peoples Hospital of Wuhan University, said that at present, there are 33 technicians and managers who are on duty in turn. It takes only 2 hours for the samples to be sent to the laboratory for real testing, but now it generally takes 4 to 6 hours to produce results. The problem lies in the delay of the information check in the early stage and the card reporting process in the later stage. She said that at present, Corey is further optimizing the process, reasonably allocating human resources and further tapping potential.
How accurate is the test?
The process of nucleic acid detection is complex, and a series of processes, such as sample transportation, data entry, reaction sensitivity control, will affect the detection time.
Many experts reported that the current detection accuracy needs to be improved. According to reports, some patients were infected with new coronavirus in terms of contact history and clinical symptoms, but the nucleic acid test of throat swab was negative. In the confirmed cases, 30% - 50% of nucleic acids were positive.
According to the reporter, in order to prevent and treat the false negative cases, for the general suspected patients in Wuhan, the new coronavirus infection was excluded only after the test result was double negative. For some suspected patients admitted to designated hospitals, if the nucleic acid test is negative for the first time, the body temperature returns to normal for more than three consecutive days, and the respiratory symptoms are significantly improved, they should be transferred to the centralized isolation point to be discharged for observation, and the second nucleic acid test should be carried out according to the requirements, and only when they are confirmed as negative can the stay be relieved.
A community director in Wuhan said that in order to make a diagnosis as soon as possible, some isolation points adopt the method of direct resampling every other day after the first sampling for the detection of suspected patients, rather than waiting for the results of two or three days before resampling as before.
In response to the problem of false negative, experts such as Zhang Xiaochun, deputy director of imaging department of Central South Hospital of Wuhan University, have called for the use of CT images as the main diagnostic basis for this new crown pneumonia, so as to timely treat and isolate highly suspected patients.
The national health and Health Commission recently issued a new diagnosis and treatment plan for pneumonia infected with coronavirus (trial version 5), which has made suspected cases with imaging characteristics of pneumonia as the clinical diagnosis case standard of Hubei Province. According to experts, clinical diagnosis cases are added as a new type for classification and treatment.
Before that, some experts of Jinyintan hospital in Wuhan had taken CT report as the first pass of disease assessment. At present, Wuhan has been improving the diagnostic methods, combining with the results of clinical imaging and reagent testing, to quickly screen suspected cases.
It is understood that at present, many institutions and enterprises are stepping up the development and production of antibody kits, which are expected to be used as an important auxiliary diagnostic means in addition to the detection of throat swab pathogenic nucleic acid, to effectively and accurately identify patients.
In addition, some front-line testing medical staff reported that at present, the quality of reagents is uneven, and the detection rate of some reagents is 60% - 70%, which may lead to missed detection of some cases with positive nucleic acids. It is understood that at present, the state is carrying out quality assessment on the testing reagents put into the market.
CT as a rapid diagnosis has its own advantages. In Hubei and other areas with severe epidemic situation, CT screening may become the first choice for diagnosis.