In the recent series of activities on the consensus interpretation of the "Chinese Journal of Infectious Diseases" of the Shanghai Medical Association, Zhang Wenhong, director of the National Center for Infectious Diseases And director of the Department of Infectious Diseases of Huashan Hospital affiliated to Fudan University, Professor Yao Duzhi, academician of internal medicine, Professor Zheng Xiaotian of Luli Children's Hospital in Chicago, Professor Hong Tao of Brown University School of Medicine - Rhode Island Hospital, and many other foreign experts focused on respiratory infection detection, diagnosis and management of respiratory infections, and prevention and control strategies of new coronavirus at home and abroad. The health industry respiratory infection frontline combs the essence of the conference for your reference.
Professor Hong Tao, Brown University School of Medicine- Rhode Island Hospital: Can a CT value really determine the virus content? Is the infection positive?
Different from China, the United States must stipulate that all testing platform sampling methods must be nasopharyngeal swabs, and most of them are oropharyngeal swabs in China.
Professor Hong Tao explained that the CT value of the United States circulated by many literature and scholars is 35, saying that this information is inaccurate. In the specimens they studied, they saw the highest CT values as high as 44 and the lowest as 9 (indicating a very high viral content). Therefore, a CT value below 45 may be considered positive.
In another set of experiments, it is observed that the virus content of the death group can be high or low, and the virus content of the survival group can also be very high, but also can be very low, and the virus is very widely distributed.
Figure 4 Distribution of CT values and virus content
Professor Hong Tao pointed out that this result has a lot to do with the way we sample.
The amount of virus on the test strips is not necessarily directly related to the amount of virus in the human body. At the beginning of the epidemic, there were a number of new coronavirus cases that were obviously pneumonia, but the tests were negative many times, because the oropharyngeal and nasal virus content was very small, and the virus content was mainly concentrated in the lungs.
At the same time, a study in which CT values were used in college students to assess the content of the new crown virus, predict the severity of the disease, and whether it was contagious, showed that 602 patients were positive, and 195 people were traced to have contact with positive patients, of which 101 were not infected and 94 were infected. It can be seen that the CT value of the virus content in the non-infectious group (green part) can be high or low; the virus content of the infectious group (red part) can also be very low, but it is infectious, so there is no obvious difference in the distribution between the two groups.
Fig. 5 CT value and virus content (whether it is infectious or not)
Fig. 6 CT value and virus content (asymptomatic)
Therefore, using CT Value to assess the viral content and infectivity of patients is a very inaccurate method, and there may be a large error. In addition, there is no direct relationship between the virus content and the presence or absence of symptoms.
Professor Yunfeng Wang, Grandi Memorial Hospital, Atlanta: A "Safety Net Hospital" for the Poor
For the new crown virus test in large public hospitals, Professor Wang Yunfeng said that their characteristic is that each state has a safety net hospital. Because the damage of the new crown to the elderly is relatively large, there are also nursing homes for the elderly.
The National Security Net Hospital is responsible for providing health care to low-income, uninsured, and vulnerable populations:
1. These hospitals are open to all patients, whether or not they have the capacity to pay, in accordance with the law or in accordance with the obligations assumed;
2. Most of the hospital's patients are recipients of the U.S. government's Medical Assistance program for the Poor, patients who are not covered by Medicare, and other vulnerable populations.
Professor Yao Duzhi, Mayo Medical Center and American Academician of Internal Medicine: A cost-effective diagnostic method for respiratory infections in third-party testing laboratories
During the pandemic phase, third-party testing laboratories were able to conduct large-scale sample testing accurately and standardly, which reduced the burden of hospital testing to a certain extent.
1. About pathogen detection options
During the COVID-19 pandemic, the main focus on third-party testing options is the patient population, the type of pathogen infected, and the state of the testing laboratory.
First of all, we must look at the patient population, consider their age, immune status, and onset period. Winter, autumn or early spring are the main periods of disease infection and epidemic, this time in the indoor opportunity is more, the population is relatively dense, the infection rate is likely to increase; in addition, for people with insufficient resistance (such as organ transplantation, cancer chemotherapy patients) are prone to infection; the elderly, young people (premature babies) and other special groups may have different infectious pathogens and other comprehensive reasons.
Second, consider the type of pathogen infected. The pathogen of infection is bacteria, fungi, or viruses. At the same time, specimens taken from different parts of the body, such as cerebrospinal fluid, lung fluid, or sputum, can affect the likelihood of a positive rate.
Third, the ability space, materials, personnel, etc. of the testing laboratory, especially the lack of reagents, test strips, personnel, instruments, etc. during the pandemic; moreover, the test turnaround time is closely related to the testing method, and whether the laboratory can publish the test results in time is a factor that needs to be considered.
2. Quick Detection option
The test option currently common in the U.S., the Rapid Test option (see Figure 1), can publish results within an hour.
Figure 1 Molecular test options for respiratory tract infection pathogens
High-throughput reagent detection options (see Figure 2) are generally fully automated, high-throughput (96 specimens can be made at a time). However, there is no fast and efficient detection time, and it generally takes 3-7 hours.
Figure 2 Molecular test options for respiratory tract infection pathogens
3. Covid-19 positivity rate decreased – Mayo Medical Center pathogen test data
Professor Yao Duzhi also shared the test data of 2,000 cases in the hospital and the proportion of their positive rate in the hospital within 2 and a half years (see Figure 3). From March 2020, the first case of new crown virus pneumonia in the United States appeared, by mid-March, the positive rate of the new crown virus was 5% to 10%, August to November 2021 was the delta epidemic period, and between January and March 2022 was the Omikeron epidemic, from the curve, the positive rate of the new crown was gradually declining.
During January and February 2020, influenza A had a positive rate of 20% to 30% for the new coronavirus, and its positive rate decreased after the arrival of the new coronavirus, and there was no positive influenza A for one and a half years, until December 2021 to February 2022, it was almost 5%, and the positive rate of influenza B was 0. Respiratory syncytial virus (RSV) has a 20% positivity rate in the summer of 2021, and the reason for this is uncertain.
Figure 3 Mayo Medical Center SARS-Cov-2, Flu A+B, RSV test requirements and data (blue bars indicate weekly tests, red dots are positive rates)
Domestic and foreign experts discussed the key points
Pathogen surveillance
Zhang Wenhong said that the first time from South Africa to monitor, we have been monitoring Aomi Kerong, it will not have a new evolution, at the beginning everyone is not very concerned, until the Omilon strain BA.2 came out, its transmission speed is surprising, so how should clinical microorganisms do this monitoring? Whether there is a capacity to do this monitoring is a question worth discussing. On the other hand, in addition to the new crown virus, what are the preparations for clinical microorganisms in our system for emerging infectious diseases in the future? Or do you want to respond after the outbreak?
Professor Wang Yunfeng believes that in the US surveillance system, the CDC of the CDC is doing sequencing very early, using sequencing data to predict the pathogen trend in the next few weeks, and to upload all the data to a unified database, which takes time. He said that although the epidemic is a bit slow in data, it still has its role to a certain extent. Overall, the monitoring of pathogens is relatively tightly tracked, and as for how to normalize in the future, it is also working in this direction.
Antigen self-test
Professor Hong Tao of Brown University School of Medicine- Rhode Island Hospital said that the sensitivity of antigen testing is much lower than that of nucleic acid testing, and there are many errors. Therefore, the two most critical points of prevention are, one is a high-quality vaccine, and the other is to wear a mask. If everyone did this, there would be no outbreak.
Professor Zeng Mei of the Children's Hospital affiliated to Fudan University said that according to the current national prevention and control standards, antigen testing will not reduce the pressure on medical staff and hospitals. Because the antigen test is positive, it is still necessary to go to the hospital for diagnosis, and the contacts around it need to be screened, and the current asymptomatic infection rate is still very high. In the past year, it will not reduce the pressure of hospital testing; but in the long run, it is still hoped that the hospital will introduce antigen testing, if the epidemic is relaxed, according to the management of Class B infectious diseases, antigen testing is very needed at the grassroots level.
At the same time, every hospital is equipped with a lot of PCR tests, and medical staff are overloaded to respond to the epidemic. Therefore, antigen testing must be widely available in outpatient clinics.
Omi kerong is not the last variant, whether the vaccine will be vaccinated every year is still uncertain, as the antigen changes, will the vaccine need to be replaced? These problems, without 5 years, it is difficult for us to develop an immunization strategy for the new crown, and we cannot establish permanent protection of immunity.
Prof. Tokushi Yao shared the guidelines for antigen testing published by the CDC of the Us Centers for Disease Control and Prevention on March 3, which are divided into conditional and non-diseased:
If it is sick and positive, it is isolated immediately; north America and China, unlike those who are positive, may be mild and can heal themselves at home.
If it is negative, it is possible that the test is not sensitive enough, so it needs to be verified by nucleic acid testing, and if the nucleic acid is positive, isolation (at least 5 days) is also required.
If it is negative and has a history of exposure, it is recommended to see if it has been vaccinated, and if it has not been vaccinated, but there is contact, although the nucleic acid is negative and antigen-negative, isolation is recommended.
Figure 9 Guidelines for CDC antigen testing recommendations
Zhang Wenhong proposed the benefits of antigen detection: in the Era of Omi kerong, the doubling of the virus in 24 hours was enough to reduce the CT value above 30 to less than 30, and the sensitivity of 2 times / day of antigen detection may be closer to the effect of 2 days of nucleic acid detection. Through the current situation of the epidemic in Shanghai, it is concluded that even if antigen testing is carried out every day, it is impossible to detect and prevent pathogens early, so a single test of antigen is not possible. If you really want to cancel the isolation, at least 2 or more antigen tests will be done to reduce the risk.
Professor Ma Xiaoling of the First Affiliated Hospital of the University of Science and Technology of China proposed that the "time" requirement should be added in response to the CT value in the ninth edition of the "Diagnosis and Treatment Plan for Novel Coronavirus Pneumonia" released on March 14, because the isolation time in foreign countries was reduced from 14 days to 10 days, 7 days, and 5 days, and finally only the CT value ≥ 35 was insufficient, and the isolation time and CT value should be jointly decided to lift the isolation time.
Zhang Wenhong said that it is very important to stay at home for 7 days after discharge, and if the patient's implementation is not strict, there is still a risk of future disease development.
Drug discussion
Zhang Wenhong: The use of the US new crown drug PF-07321332/ritonavir tablets Paxlovid is after the epidemic in the United States has been better reduced, out of consideration for the necessity of this drug, how much role does the listed drug play?
Professor Wu Fan of Columbia University Medical Center said that drug sales only began in New York on March 1, when the epidemic case curve was already declining, because the symptoms were relatively mild, and patients basically healed themselves when they were at home. On the other hand, some time ago, home surveillance was just beginning, and the vast majority of unreported phenomena will also affect the statistics of the number of cases.
Vaccinations
Zhang Wenhong believes that from the perspective of the current situation of the global epidemic situation, for the strengthening of the injection vaccine, it is first necessary to evaluate and optimize, as to whether the optimized immunization strategy is sufficient, whether it will be strengthened regularly in the future, it is still uncertain. However, for some high-risk, vulnerable groups, their antibodies can be tested and then regularly (half a year or one year, depending on the data) injections can be given. For ordinary people, in the epidemic environment, the third needle is very important. With regard to the fourth dose of vaccination, the main concern is the protection of vulnerable people, and it is highly recommended that vulnerable people receive a fourth dose.
Resources
[1] How to achieve accurate monitoring in the face of "cunning" respiratory pathogens? Guangxi Autonomous Region People's Hospital public number.2022-03-23 21:38
Health community – the front line of respiratory infections
Li Tong, | author of the article
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