Saturday, June 27, 2020

Diversified viral transmission paths in the Beijing second wave of epidemic

Report by : Gan Yung Chyan
                 / KUCINTA SETIA

After this round of large-scale SARS-CoV-2 (covi, in short) nucleic acid screening in Beijing, the transmission chain related to Xinfadi Market has been controlled, and experts believe that there is still a two-week sweep period. At the same time, the cases of covid in society will also enter a normalized state of prevention and control.

As at 12 am  on 28 June, Beijing newly reported 14 local confirmed cases and 4 asymptomatic infections, with no new suspected cases. Since 11 June, Beijing has reported a total of 311 local confirmed cases. 25 cases of asymptomatic infections still under observation.

At the 134th press conference of Beijing's novel coronavirus pneumonia (covid) epidemic prevention and control work on June 27, Xu Hejian, deputy director of the Beijing Municipal Party Committee Propaganda Department, director of the Municipal Government Information Office, and municipal government news spokesman, said, "The epidemic situation in the capital is severe and complex Nothing can be taken lightly. From the case analysis, circulatory results, and transmission trajectory since the cluster epidemic occurred in the Xinfadi wholesale market, the industry scenarios, approaches, and symptoms involved are complex and diverse, and we cannot be taken lightly or paralyzed. People's carelessness and paralysis may cause new problems."

Diversified transmission paths

All along, respiratory transmission and mucosal contact transmission are considered to be the main routes of transmission of SARS-CoV-2, but the Beijing covid epidemic that began on 11 June, regardless of the scene or path of transmission, is more diversified.

With Xinfadi aquatic products as the core, the scene of Beijing's covid spreads continuously, from the market to the restaurant, from salmon to beef and mutton, including public toilets.

On 25 June, when a new case was transferred from the Haidian District Center for Disease Control and Prevention in Beijing on June 21, it was found that the infection route of the confirmed case was locked as a public toilet at No. 70 Yongding Road.

Public toilets have become the spread scene of covi, which is the first case after the emergence of the novel coronavirus.

As early as 13 February, Guangzhou Medical University, Guangzhou Customs and Zhongshan No. 5 Hospital isolated the virus from the feces of patients with covid. Dr. Tang of Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology has previously called for vigilance against the possibility of the transmission of covi through human excreta (such as feces and urine). He believes that this aspect has not been given enough attention, because previously only sputum was used. An important method of transmission is mainly to detect nucleic acid in sputum in the diagnosis experiment, plus some auxiliary tests such as blood routine, liver function, kidney function, etc., but excrement has not attracted attention.

 "There is currently no evidence that SARS-CoV-2 is transmitted through the fecal orifice, but the live virus in the feces can enter the air to form an aerosol and then be infected through the respiratory tract, so the elimination of the environment is very important." A virologist said.

According to the paper "Aerosol and surface stability of HCoV-19 (SARS-CoV-2) compared to SARS-CoV-1" published by the National Institute of Allergy and Infectious Diseases under the National Institutes of Health on 10 March, covi survives up to 3 hours in air aerosols, with a median half-life of 2.7 hours; it can survive 24 hours on paper materials, up to 4 hours on copper surfaces, and 2-3 days on plastic and stainless steel surfaces.

According to the current understanding of the survival time of covi the People's Republic of China has also made relevant regulations on the cleaning and disinfectation  of public toilets. "If strictly implemented, it may reduce the chance of infection." An urban sanitation worker said.

In response to the epidemic of new coronavirus pneumonia, on 12 February, the Public Toilet Construction Management Committee of the China Urban Environmental Hygiene Association (referred to as the "Central Association Public Toilet Committee") compiled the "Guidelines for Disinfection of Public Toilets during the New Coronary Pneumonia Epidemic" to prevent and control the outbreak During the cleaning and disinfection of public toilets during the period, to ensure the safety of public toilet management personnel and manure removal and transportation personnel, and to do a good job in the closed collection and transportation of manure and harmless treatment, etc. At the same time, the frequency of killing and killing is regulated, and cleaning personnel are required to disinfect once every 3 hours during the opening of public toilets. The frequency of disinfection can be increased or decreased according to the flow of people.

On 11 March, the State Council Joint Prevention and Control Mechanism held a press conference on strengthening the comprehensive treatment of medical waste and protecting the ecological environment. At the meeting, Liu Lifeng, deputy director of the Urban Construction Department of the Ministry of Housing and Urban-Rural Development, said that during the epidemic in Beijing, more than 6,000 public toilets in the city remained open 24 hours a day, doubling the frequency of killing.

Xinfadi control chain

From 0:00 to 24:00 on June 26, Beijing newly reported 17 local confirmed cases, 13 of which were on "12 June transferred from a special vehicle to a centralized isolation point for centralized medical observation, and the nucleic acid test result was positive on 24 June. ."

The 13 cases of "centralized medical observation" once again reflect the timeliness of Beijing's prevention and control measures.

After the emergence of the case on 11 June 11, Beijing quickly locked up the new market, isolated the relevant personnel, carried out medical observations, and expanded the nucleic acid screening population. Through a series of prevention and control measures, the people related to the new development are under control.

"The people with the disease are within our control. We already know where they are and who they are, which is the most critical." Wu Hao, an expert from the Expert Committee on Disease Prevention and Control of the National Health and Health Commission and the chief expert of Beijing Community Health, said if there are confirmed cases, it will continue for a while. "According to the incubation period, I estimate that it will not exceed next week."

Wu Hao judged that the epidemic in Beijing has entered a stable period.

"From the data point of view, it may be a stationary period, and the number of new patients is maintained at a certain number every day. The stationary period does not mean that no new cases occur, but the results of the nucleic acid test results done in the early stage will gradually come out." Wu Hao said. It also depends on the nucleic acid test results of those who have not been to the risk area or have contact with the risk group. If there is no problem, basically all sources of infection can be considered to be from Xinfadi.

In Beijing's covid prevention and control, rapid mobilization and detection played an important role.

In addition to the population related to Xinfadi, nucleic acid screening for key populations in other industries is also underway. At a press conference on 27 June, Wang Hongcun, a second-level inspector of the Beijing Municipal Commerce Bureau, said that at present, 10,765 hairdressing and beauty business entities have been investigated in Beijing, 26,286 nucleic acid samples have been completed, and 12,350 have been tested, all of which are negative.

Wang Hongcun also said that all hairdressing and beauty companies obey the street and township arrangements in the area where the store is located, and actively do the follow-up nucleic acid detection work of practitioners, so as to "examine thoroughly." In the next step, the district governments should continue to implement territorial responsibility, and hairdressing and beauty companies should obey and cooperate with the market supervision and comprehensive law enforcement departments to carry out law enforcement inspections and jointly implement the new guidelines. At the same time, in accordance with the principle of "should be eliminated, should be exhausted", continue to organize a good inspection of the epidemic prevention safety in the hairdressing and beauty industry, to create a safe and secure consumer environment for consumers.

SARS-CoV-2 may coexist with humans for a long time. How to normalize prevention and control next?

"Wuhan didn't know much about the virus at that time, so I pressed the pause button under certain conditions. This time, because I had a lot of good experience and models to use, I took rapid and precise control. The most important thing is Yes. Early detection was done this time. So far, according to relevant evidence, no community-based spreading spread has been seen, which is crucial." Wu Hao said.

However, Wu Hao also said that the control of the epidemic does not mean that there are no confirmed cases. The prevention and control must continue, and everyone should not continue to be slack. "This is why we say normalization prevention and control, not normalization of life."


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