Why does the wholesale market easily become an outbreak point? Expert: The lower the temperature, the longer the virus will survive

Five confirmed cases of COVID-19 have been reported from 0:00 to 24:00 on June 12 in Fengtai District, Beijing.
The course of action of the case involves some merchants in the wholesale market of Xinfadi. Currently, closed management measures have been taken in the wholesale market of Xinfadi and the surrounding communities.

On June 13, four new confirmed cases of COVID-19 were announced in Beijing, with their movements pointing to the same place — xinfadi Wholesale market for agricultural products.
At the same time, novel Coronavirus nucleic acid positive tests were found in the new Hair market practitioners and the environment.

Novel Coronavirus has not reported new confirmed cases in Beijing for more than 50 days. Where did novel Coronavirus come from?
Why does the outbreak point to the wholesale market?
The reporter interviewed Wu Zunyou, chief epidemiologist of The Chinese Center for Disease Control and Prevention.

Low temperature environment, dense population easily lead to virus transmission

Q: Why does the outbreak in Beijing point to the wholesale market?

Zunyou Wu: When our researchers collect biological samples with virus on a daily basis, they usually keep them in low temperature.
The colder the temperature, the longer the virus lives.
In wholesale markets, where much seafood is stored frozen, the virus can survive for a long time and is more likely to infect humans.
In addition, a large number of people enter and leave the wholesale market of agricultural products every day. As long as one person is carrying the virus and enters the market undetected, it may cause the spread of the epidemic.

According to previous knowledge and experience, there are two possibilities for a sudden outbreak of coVID-19 in Beijing.
In the first possibility, seafood or meat contaminated with a novel Coronavirus in a wholesale market is the source.
Wholesale market a lot of seafood, beef and mutton are not Beijing real estate, but the field import, including overseas imports.
At present, there are hundreds of thousands of new coronavirus infections every day in the world. Novel Coronavirus infection may cause contamination when dealing with seafood or beef or mutton.
After these products are delivered to the wholesale market in Beijing, the wholesale market people will touch these products when they operate.
We know that novel Coronavirus is mainly through droplet transmission and contact transmission.
If they touch the contaminated product and rub their nose and eyes, they become infected.
The symptoms are mild at first and can spread from person to person at work if not realized.
The second possibility is that there are other sources of infection.
The wholesale market in Xinfadi has a large flow of people, and the people in the market come from all directions. Those who come and go in the wholesale market in Xinfadi are the source of infection.

For example, he may be a person who came from another epidemic area. After being infected with mild symptoms, he did not pay attention to it at that time, and then caused pollution to the wholesale market in Xinfa, which led to the agglomeration of the epidemic.
As several cases have been found so far linked to the wholesale market in Xinfa, attention has been turned to Xinfa.
Whether contaminated seafood or meat in the market was the original source of the infection, or whether people entering or leaving the market were the source, both possibilities exist.
But the first scenario is more likely based on what is happening in Beijing.

To do this, we need to collect data from the following aspects.
First, after collecting complete information on all infected persons and close contacts, the contact relationship, transmission chain and transmission network between people should be established, which is an epidemiological investigation.
The second is to rely on big data to tease out the movements of all those infected, which can give us clues as to whether they share a common exposure, such as the presence of several confirmed patients in the past few days somewhere near the site of the outbreak.
The third is biotechnology in the laboratory, which studies the genetic sequence of viruses to help determine their likely origin.
Study and analyze the virus gene of the extracted sample to see whether it is the same as the novel Coronavirus that appeared in Beijing two months ago, or more similar to Harbin and Shulan, or more similar to the virus strains prevalent in America and Europe.
These analyses can provide us with more information.
In short, if we combine these three approaches, we can have a clearer understanding of the new outbreak in Beijing.
It is still in the process of gathering information, and there is no way to draw a firm conclusion.

It is impossible to determine the source of infection in the wholesale market

Q: What is the source of contagion in the wholesale market?
Is it the flow of people or logistics?
Meat, fish, or something?
Can you make an analysis from the perspective of epidemiological investigation?

Wu Zunyou: At present, it is difficult to determine the source of infection in the wholesale market.
For example, just because a novel Coronavirus is detected in the chopping board of imported salmon, we cannot conclude that salmon is the source of infection.
Anyone or anything that comes in contact with the chopping board is likely.
For example, a novel Coronavirus infected person may be the owner of the chopping board.
For example, a guest may purchase from a novel Coronavirus infected person. If he spends a long time in front of the chopping board, he may cause contamination of the chopping board when communicating with his host or bargaining.
For example, a novel Coronavirus may be contaminated with another item sold by the board owner.
We need to collect samples from different channels to verify and evaluate which one is more likely.
Xinfadi wholesale market stream of people, sales of goods too many too complex, not in a very short time to be able to understand clearly.
Only by checking all the people and objects can we show the whole picture.

Before this new outbreak, There had been no confirmed cases in Beijing for more than 50 days in a row.
If epidemiological investigation and big data analysis confirm that none of the confirmed coVID-19 cases and those positive nucleic acid tests have a history of travel, and they are all actually infected in Beijing, then it is likely that the virus was brought in by imported or contaminated items outside Beijing.
So, must carry on careful and meticulous carding to new hair place article source channel.

Carrying wild animals and carrying imported goods are two different concepts

Q: Some analysts say that seafood is unlikely to be a source of infection, because fish are low living things and fish viruses rarely infect people. That means salmon itself is very unlikely to be a carrier of the virus.
What do you think about that?

Wu Zunyou: There is some truth in this analysis, but it’s not all right.
Carrying wild animals and carrying imported goods are two different concepts.
Civet cats, bats and other wild animals can carry the coronavirus themselves, and the virus multiplies in them without getting sick.
Imported items carried mean that the worker infected by a novel Coronavirus contaminated the items when handling them. After the contaminated items were imported into China, others became infected during processing.
So wildlife carries the virus, and seafood carries the virus on contaminated surfaces.
Fish do not carry coronavirus in their bodies.
However, after the fish was caught, the contaminated seafood may contaminate the surface of the fish because the processing worker was infected with a novel Coronavirus, and the contaminated seafood was transported to China. The infected seafood was infected during the processing of the fish and further spread from person to person.
Of course, this is just a speculation, which needs further confirmation from epidemiological investigation.

Under the current situation, it is necessary to do a good job in the inspection and quarantine of fresh, fruits and vegetables and other goods.
Two situations are of particular concern: one is for goods imported from abroad.
At present, the epidemic situation overseas is more serious than that in China.
The other is frozen goods, including seafood, beef and mutton.
In all these cases, quarantine should be strengthened.

The key is to prevent and control the epidemic

Q: What is critical now is to make it controllable through our streaming, traceability, detection and screening. How?

Wu Zunyou: The epidemic started early in Our country and we had little experience in fighting the epidemic. The reason why we were able to control the epidemic was that we resolutely and thoroughly implemented 100 percent of the measures to control respiratory infectious diseases.
Under the most severe conditions in China at that time, all provinces, autonomous regions and municipalities, including Beijing, were able to control the epidemic without causing it to spread more widely.
Now, with a few more sporadic cases, we are confident that we can deal with the outbreak in the bud in a timely manner and not cause a wider spread.
Harbin and Shulan are like this, and so will Beijing.
We have confidence.

Different people may have different understandings of the four words “controllable”.
“Controllable” does not mean that a case will not occur. It means that even if a case does occur, we will be able to detect and deal with it in the first place, so as to keep the epidemic within a minimum range. That is what we mean by “controllable”.
Novel Coronavirus is a new infectious disease so contagious that patients do not realize they are infected until a few days after they have symptoms. When they are diagnosed in the hospital, the virus has often caused a certain range of transmission and spread, so it is extremely difficult to control.
Therefore, “preventable and controllable” does not mean zero cases, zero transmission and zero deaths. We should also have a clear and rational understanding of these four words.

Beijingers need not panic

Q: What is the risk of the virus spreading in the current situation?

Wu Zunyou: Fighting coVID-19 is like fighting a war. Every second is precious.
Get the virus under control before it spreads, and you have the upper hand.
Take the provinces outside Hubei as an example. Why didn’t any provinces and municipalities experience the same situation as those in Europe?
Key lies in the fact that flowed from hubei to return to the local, we first mastered their situation, take the initiative to contact, the vast majority of them, before they had not yet developed symptoms have been isolated under medical observation, once the symptoms for treatment immediately, not let them stay in society too much, not wait until after they come on again to go to the hospital, not give these people from hubei infection time at a local outbreak spread, it is working.

The immediate priority is to identify the source of the infection as early as possible, identify close contacts and avoid secondary transmission. Beijing has responded quickly.
A few sporadic cases, can be analyzed in such a short time, lock xinfa wholesale market.
The experience of the past few months, especially the use of technology such as big data, has enabled us to quickly point in the right direction.
After the direction was determined, the personnel and environment were immediately tested, and more directional information was quickly obtained.
These important information will not only be of great significance to Beijing’s epidemic prevention and control, but may also provide new and valuable information to unravel the mystery of the spread of coVID-19.
I have full confidence in Beijing’s prevention and control of the epidemic.
Of course, there is still a lot of work ahead and we need to continue to work hard.
The number of close contacts is still very large, and a slight omission could pose a risk of spread.
So a lot of people have to be involved in the search for close contacts.
At the same time, the laboratory should carry out testing and analysis as soon as possible to provide more decision-making basis for epidemic prevention and control.

According to the current information, the rebound of the epidemic in Beijing is mainly concentrated around the markets in Xinfadi.
For employees and family members working in Xinfang, close contacts, medical staff in hospitals, and patients visiting the hospital at the same time, it is more accurate to extend the nucleic acid test to these ranges.
The virus has so far not spread to the whole of Beijing, threatening the city’s more than 20 million people.

Q: Under the current situation of epidemic prevention and control, what should Beijing citizens pay special attention to?

Wu Zunyou: There is no need for people to panic. After all, we have accumulated rich experience in epidemic prevention and control and treatment of patients.
The city has taken a series of measures, including publishing the activity tracks of confirmed cases and defining the response levels in some areas.
By pinpointing this information, people can tell if they have been to any of these places in the past week or two.
People who have been to observe their physical conditions, to see if there are abnormalities, not at ease can take the initiative to do nucleic acid testing.
For other citizens, in places with poor ventilation, basic hygiene habits such as wearing masks and washing hands should be maintained.

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