Four questions about high-frequency large-scale nucleic acid testing in Shanghai

　　Since the new round of the epidemic, Shanghai has implemented high-frequency nucleic acid screening for some time.

Starting from the 15th, Shanghai will carry out "antigen + nucleic acid" combined detection and screening for all personnel in the closed control area and control area, and conduct antigen detection and screening for all personnel in the prevention area; from the 18th to the 21st, the closed control area will continue to Nucleic acid testing was carried out in four days.

　　Why is high-frequency nucleic acid detection screening necessary?

How to prevent cross infection in screening?

How to make nucleic acid detection more convenient and efficient?

To coordinate the next step of resumption of work and production, how to meet the normalization needs of nucleic acid testing?

... In response to the issues that citizens have focused on and reported recently, Xinhua News Agency reporters interviewed relevant departments and experts in Shanghai.

Question 1: What is the significance of high-frequency nucleic acid detection screening?

Why is it necessary to carry out nucleic acid testing for several consecutive days in the sealed area?

　　Gao Chunfang, director of the Laboratory Center of Yueyang Hospital Affiliated to Shanghai University of Traditional Chinese Medicine, said that high-frequency nucleic acid testing is very necessary.

From the perspective of the occurrence and development of clinical diseases, any pathogen infection has a certain incubation period, and the new coronavirus is no exception, and there are certain individual differences in the length of the incubation period.

From the perspective of detection technology, there is a growth and replication process in the human body after virus infection. If the viral load in the early stage of infection is lower than the detection limit, the positive is difficult to be found. This time period is the detection window period.

The "incubation period + detection window period" makes it impossible to detect positive results in the early stage of infection.

Therefore, repeated tests can increase the probability of positive detection and detect positive in time.

　　At the same time, since the sampling of respiratory pathogens mainly adopts several forms of throat swab, nasal swab, and nasal + pharyngeal swab, there are inevitably certain sampling differences in the sampling process.

Such differences include sampling site, depth, and amount of collected secretions.

Therefore, repeated sampling and testing can compensate for the possible false negative effects caused by sampling errors.

　　Hu Xiaobo, director of the Shanghai Clinical Laboratory Center, said that when it comes to community screening, when the community completes a round of nucleic acid screening, usually those infected with a higher viral load can be screened, but there are also some with a lower viral load. Infected people will show negative nucleic acid results at the initial stage, and they can only be detected through testing when more and more virus replicates in their bodies.

The latter, if not detected in time, may become potential spreaders in the community.

Therefore, it is necessary to dynamically detect positive infections as soon as possible through multiple rounds of nucleic acid screening in a row, and realize the dynamic clearing of social aspects as soon as possible.

Second question: How to prevent cross-infection in large-scale nucleic acid detection and screening?

　　Wu Qing, member of the Standing Committee of the Shanghai Municipal Party Committee and executive vice mayor, said that in terms of resource allocation, utilization and scheduling organization for large-scale screening, Shanghai has organized various streets, towns and communities to set up sampling points reasonably, and try to do a good job in the organization and mobilization of residents. Many The districts have adopted a series of organizational methods including "do not call, do not call, move again when called", "go to the door when you need to go, go downstairs when you need to go downstairs", "divide by door, by time period, and by batch".

At the same time, guide residents to strictly abide by the "2-meter line" spacing, wear masks, and not communicate during the testing process to avoid cross-infection.

　　Zhao Dahai, a professor at the School of International and Public Affairs of Shanghai Jiaotong University and executive director of the Shanghai Jiaotong University-Yale University Joint Research Center for Health Policy, said that by optimizing the methods and methods of nucleic acid testing, residents are organized to participate in nucleic acid testing in an orderly manner in different periods and batches, reducing the number of Gathering of people can effectively prevent cross-infection.

Three questions: How to make large-scale nucleic acid testing more convenient and efficient?

　　In terms of sampling power, Shanghai has required all districts to conduct grid screening to find out the actual population in the screening area, and reasonably allocate sampling medical staff.

Taking April 16 as an example, Shanghai invested nearly 25,000 sampling medical staff, including more than 12,000 medical staff from Jiangsu, Zhejiang, Anhui and other places.

With the support and help of the sister provinces and cities, the large-scale nucleic acid screening has been completed on time and according to the quantity in the past few days.

　　In terms of testing strength, on the one hand, Shanghai has enhanced its nucleic acid testing capabilities through rapid new gas membrane laboratories and mobile nucleic acid testing vehicles; Accepting aid from other provinces and cities for construction and sending samples to sister cities, etc., have further enhanced testing capabilities.

　　At present, Shanghai has a maximum detection capacity of nearly 5 million tubes per day, and more than 2,000 sample transfer vehicles have been deployed to speed up sample transfer.

Fourth question: How to coordinate the resumption of work and production in the next step, how to meet the normalization needs of nucleic acid testing?

　　Wu Qing said that Shanghai is currently planning and laying out a nucleic acid detection method that combines "fixed sampling points + convenient sampling points + mobile sampling points" according to regional population density and functional positioning, and coordinate the setting of normalized sampling points.

　　The fixed sampling points are mainly about 200 existing medical institutions in Shanghai; the convenient sampling points are mainly set up in the form of "books and newsstands"; the mobile sampling points are mainly based on the form of "breakfast carts". Sampling vehicles and other forms improve mobility and mobility.

　　Fixed, convenient, mobile and other sampling point facilities will be mainly located in residential areas, transportation stations (such as subway entrances, bus stops, airports, ports, high-speed rail, bus stations, etc.), CBD parks and other office areas, large construction sites, Schools, large supermarkets, medical stores and other surrounding areas.

For places with a lot of people, try to choose a relatively independent site that is open, with better ventilation conditions.

(Reporters Yuan Quan and Hu Jiefei)