Why does the outbreak point point to the wholesale market? What is the source of infection? CDC Expert Response

On June 12, from 0:00 to 24:00, a total of five confirmed cases of new coronary pneumonia were reported in Fengtai District, Beijing. The course of the case action involves some merchants in the wholesale market of new origin, and closed management measures have been taken in the wholesale market of the new origin and the surrounding district. On June 13th Beijing announced four confirmed cases of new crown pneumonia, with a trajectory that points to the same place, the wholesale market for agricultural products in Xindai. At the same time, the new origin market practitioners and the environment detected positive for the new coronavirus nucleic acid.

Why does the outbreak point point to the wholesale market? What is the source of infection? CDC Expert Response

Source: Cop China

Beijing, which has not reported a new confirmed case locally for more than 50 days, where did the new crown virus come from? Why does the outbreak point point to the wholesale market? The reporter interviewed Wu Zunyou, chief epidemiologist at the China Center for Disease Control and Prevention.

Low temperature environment, dense flow of people easy to lead to the spread of the virus

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

Wu Zunyou: When our researchers collect biological samples with viruses on a daily basis, they usually store them at low temperatures. The lower the temperature, the longer the virus survives.

In the wholesale market, many seafood are frozen, in this environment, the virus can survive for a long time, the risk of infecting people is greater. In addition, the wholesale market for agricultural products has a large number of people in and out every day, as long as one person is carrying the virus, if not detected and enter the market, it may cause the spread of the epidemic.

Based on past knowledge and experience, there are two possibilities for a sudden outbreak of a new crown in Beijing. The first possibility is that seafood or meat contaminated with the new coronavirus in the wholesale market is the source. Wholesale market many seafood, beef and mutton, etc. are not Beijing native real estate, but imported from abroad, including overseas imports. There are now hundreds of thousands of new crown cases worldwide every day, and new crown virus infections can cause contamination when dealing with seafood or beef and mutton. After these products are shipped to the wholesale market in Beijing, the people in the wholesale market will come into contact with these products when they operate. We know that the transmission of the new coronavirus is mainly the spread of droplets and contact transmission. Their hands come into contact with contaminated products, and then rub their noses and rub their eyes, they become infected. The symptoms are mild at first, and if you don’t realize it, it can also cause human transmission at work.

The second possibility is that there are other sources of infection. The new origin wholesale market traffic is very large, the market personnel from all directions, access to the new origin wholesale market is the source of infection. For example, he may be a person from other sources of the epidemic, after the infection of the symptoms are very light, he did not pay attention to at the time, and then caused contamination of the wholesale market in the new origin, resulting in the concentration of the outbreak. Since several cases are currently found to be linked to the wholesale market in the new origin, attention has been turned to the new origin. Both may exist as to whether contaminated seafood or meat in the market is the initial source of infection or whether the people entering or leaving the market are the source of the infection. But based on Beijing’s current situation, the first is more likely.

To do this, we need to collect data on the following areas.

First, all infected persons, close contacts of the information collection complete, the human-to-human contact relationship, transmission chain, communication network to build up, this is the epidemiological investigation.

The second is to rely on big data technology, all infected people’s action trajectory combed out, their trajectory can give us some hint sifthoped, such as several confirmed patients have been in the new place of the past few days near the new place.

Third, laboratory biotechnology helps to determine the possible origin of viruses by studying the genetic sequences of viruses. The samples were studied and analyzed to see if it was the same as the new coronavirus that appeared in Beijing two months ago, or more similar to Harbin and Shulan, or closer to the virus strains prevalent in the United States and Europe. Through these analyses, we can provide more information. In short, the combination of these three methods, can be beijing’s new outbreak of a clearer understanding. At present, in the process of gathering information, there is no way to give a definite conclusion.

It is not possible to determine the source of infection in the wholesale market at this time

Q: What is the source of infection in the wholesale market? Is it the flow of people or logistics? Is it a meat fish or something? Can we analyze it from the perspective of epidemiological investigation?

Wu Zunyou: It is still difficult to determine what the source of infection in the wholesale market is. For example, we can not because of the cutting of imported salmon in the case board detected the new crown virus, we conclude that salmon is the source of infection. It is possible for anyone or object son who has access to the case board. For example, perhaps the owner of the case board is a new crown virus infection, he dropped on the case board during the speech, for example, the guests who may come to purchase are the new crown virus infection, he spent a long time in front of the case board, in the course of communication with the owner or cut prices, may also cause the case board to be contaminated;

Samples need to be collected from different channels to verify that it is more likely to assess which one is more likely. The new origin wholesale market is crowded, the variety of items sold is too many too complex, not in a short time can be clearly. It is only when all the people and objects are checked out that it is possible to show the whole picture.

Before the new outbreak, Beijing has been more than 50 consecutive days without a local confirmed case, according to reason, there should be no virus here. If epidemiological investigation and big data analysis confirm that the newly confirmed cases of new crown and nucleic acid test positive people have no history of going out to move, they are actually infected in Beijing, then there may be imported or contaminated items outside Beijing to bring the virus in. Therefore, be sure to new hair source channels carefully combed.

Wildlife carrying and imported goods

It’s two different concepts.

Q: Some analysts say that seafood is unlikely to be a source of infection, because fish as a low-class organism, fish virus transmission to humans has rarely occurred, that is to say, salmon itself as a carrier of the virus is very unlikely. What do you think of this?

Wu Zunyou: This kind of analysis has some truth, but not all right. Wildlife carrying and imported goods carrying are two different concepts. The wild animals, such as beavers and bats, can carry the coronavirus itself, which breeds in their bodies without developing it. Imported goods are carried by workers infected with the new crown virus when the goods contaminated these items, contaminated goods imported into the country, other people infected in the process.

So wild animals are carrying viruses, seafood is contaminated after the surface carrying viruses. Normal nature fish do not have coronavirus escants in their bodies. But after the fish is caught, because the workers infected with the new crown virus, may lead to the surface of the fish contaminated, and contaminated seafood is shipped to China, Chinese workers in the process of treatment infected, resulting in further human-to-human transmission. Of course, this is only a guess that requires further confirmation by epidemiological investigation.

Under the current situation, it is necessary to do a good job in the inspection and quarantine of fresh, fruit and vegetables and other goods. In particular, two situations should be paid: one is an item imported from overseas. At present, overseas outbreaks are more serious than in China, and imports from countries with severe outbreaks should be given extra attention. The other is frozen transport items, including seafood, beef and mutton. In these cases, quarantine needs to be strengthened.

The key to anti-epidemic is to be preventable and controllable.

Q: Now it is critical to pass our flow, traceability, detection, troubleshooting, so that it can be controlled, how to do this?

Wu Zunyou: The outbreak occurred early in our country, when the experience of anti-epidemic is also small, we were able to successfully control the epidemic, because we firmly and thoroughly put the method of controlling respiratory infections in place 100 percent. At that time, china’s worst outbreak, provinces and cities, including Beijing, were able to successfully control the outbreak, did not cause the spread of the epidemic to a wider extent. Now, with some more sporadic cases, we are confident that the outbreak will be dealt with in time without causing a wider spread. Harbin, Shulan are like this, and so will Beijing. We have confidence.

For the “anti-controllable” four words, different people may understand different. “Preventable control” is not to say that a case does not appear, but to say that even if there is a case, we can first find, the first time to deal with, so that the outbreak is kept to a minimum, this is what we mean “preventable and controllable.”

The new coronavirus is a new infectious disease, it is so infectious, patients only after the appearance of symptoms a few days before they realize that they are infected, when they are diagnosed in the hospital, often has caused a certain range of transmission and spread, so it is extremely difficult to control. Therefore, “preventable and controllable” does not mean zero case zero transmission zero death, we must have a clear, rational understanding of these four words.

Beijing residents don’t have to panic.

Q: In the current situation, what is the risk of the spread of the virus?

Wu Zunyou: Responding to the new crown outbreak is like a war, a minute is extremely precious. Grab the virus before it spreads out to bring it under control, then you have the initiative.

In the case of provinces and cities outside Hubei, why hasn’t any province or city in Europe ever been in a situation like this? The key is that people from Hubei flow back to the local, we first grasp their situation, active contact, the vast majority of them, before they have not yet appeared symptoms have been isolated for medical observation, once the symptoms immediately treated, did not let them stay in the community too much, did not wait until they became ill before going to the hospital, did not make these people infected from Hubei have time to cause the spread of the epidemic in the local, this is time to seize time.

Soldiers, as early as possible to determine the source of infection, check close contacts, to avoid secondary transmission, is the focus of the current, Beijing’s response speed has been very fast. Several sporadic cases can be analyzed in such a short period of time to lock in the wholesale market of new origin. The experience of prevention and control over the past few months, especially the use of technical techniques such as big data, has enabled us to quickly align our direction. After determining the direction, the people and the environment are immediately tested, and more pointed information is quickly obtained.

This important information is not only of great significance for the prevention and control of the outbreak in Beijing, but also may provide new and valuable information for solving the mystery of the spread of the new crown epidemic. I have full confidence in the prevention and control of the outbreak in Beijing. Of course, the work ahead is still difficult and needs to continue. Close contacts are still very large, a little negligence omission, will cause the risk of spread. Therefore, a large number of personnel also have to invest in close contact search and investigation. 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.

From the information known so far, the Beijing outbreak rebounded, mainly concentrated around the new origin market. The expansion of nucleic acid testing to these areas is more accurate for employees and family members working in the new places, close contacts, as well as medical staff at the hospital, and patients attending at the same time. The current scope of the virus’s activities has not spread throughout Beijing, and has not threatened the city’s more than 20 million people.

Q: In the current situation of epidemic prevention and control, what do the citizens of Beijing need to pay special attention to?

Wu Zunyou: There is no need to panic, after all, we have accumulated rich experience in epidemic prevention and control, patient treatment and so on.

At present, Beijing has taken a series of measures, including the publication of confirmed cases of activity trajectory, defined some regions of the response level. By defining this information precisely, people will know whether they have been to these places in the past week or two. People who have been to observe their physical condition to see if there are abnormal, not assured can actively apply for nucleic acid testing. For other citizens, in poorly ventilated places, basic hygiene practices such as wearing masks and washing hands frequently should be maintained.