The novel coronavirus pneumonia prevention and control expert group member Yang Peng, a researcher at Beijing CDC, said that the source of the virus in Beijing’s new hair site is still under investigation. “Through the whole genome sequencing, it was found that the virus came from the European direction, and it was preliminarily determined that it was related to the import. But it’s not clear how the virus came. It could be contaminated seafood or meat, or people entering the market could spread it through secretions. “
Previously, Zeng Guang, former chief researcher of epidemiology of China CDC, revealed that in the two samples of new coronavirus that had been tested at that time, it was found that the virus was not like the domestic native virus, and it was preliminarily determined to be a European new coronavirus variant.
“But the final determination of whether the new coronavirus in the Beijing epidemic is a native virus requires more sample test results.” Zeng added.
In recent days, there have been confirmed cases in Beijing, and the wholesale market of agricultural products in Xinfadi has become an outbreak point. Beijing, which has not reported new confirmed cases for more than 50 days in a row, where does the new coronavirus come from? Why does the outbreak point to the wholesale market? Wu Zunyou, chief epidemiologist of China Center for Disease Control and prevention, responded to many questions from the public.
Why does the local outbreak point to the wholesale market in Beijing?
Wu Zunyou: the lower the temperature, the longer the virus will survive. In the wholesale market, many seafood are frozen. In such an environment, the virus can survive for a long time, and the probability of infecting people is greater. In addition, there are a large number of people in and out of the wholesale market of agricultural products every day. As long as one person carries the virus, if it is not found and enters the market, it may cause the spread of the epidemic. According to previous knowledge and experience, there are two possibilities for the sudden emergence of a new local epidemic in Beijing.
The first possibility is that seafood or meat contaminated with the new coronavirus in wholesale markets is the source. Many seafood, beef and mutton in the wholesale market are imported from other places, including overseas, rather than from Beijing. At present, there are hundreds of thousands of new coronavirus cases every day in the world. People infected with new coronavirus may cause pollution when they deal with seafood or beef and mutton. After these products are transported to the wholesale market in Beijing, when people in the wholesale market operate, they will be infected if they touch the contaminated products with their hands and rub their noses and eyes. At first, the symptoms are mild. If you don’t realize it, you may also create human to human transmission at work. The second possibility is that there are other sources of infection. The flow of people in Xinfadi wholesale market is very large. The people in the market come from all directions. The people in and out of Xinfadi wholesale market are the source of infection. For example, he may be a person who came from other epidemic areas. After being infected, his symptoms were very mild, and he didn’t pay attention to it at that time. Since then, he has caused pollution to the wholesale market of the new epidemic areas, leading to the concentration of the epidemic situation.
According to the current situation in Beijing, the first situation is more likely.
What is the source of infection? It’s hard to tell
Wu Zunyou: at present, it’s difficult to determine the source of infection in the wholesale market. For example, we can’t conclude that salmon is the source of infection because new coronavirus is detected in the chopping board of imported salmon. It is possible for all people or objects to come into contact with the board.
Maybe the owner of the board is a new crown virus infector, and his droplets fall on the board during his speech; maybe the customer who comes to purchase is a new crown virus infector, who has been in front of the board for a long time, and may cause the board to be polluted during his talk or bargaining with the owner; maybe other items sold by the owner of the board are polluted with a new crown Virus can also contaminate the board.
Xinfadi wholesale market has a large flow of people, and the products sold are too many and complex to be sorted out in a short time. Only when all the people and objects have been checked out can the whole picture be displayed. Before the new outbreak, Beijing had no local confirmed cases for more than 50 consecutive days, and there should be no virus here. If the epidemiological investigation and big data analysis confirm that the confirmed cases and nucleic acid test positive persons found at present have no history of going out and moving, and they are all infected in Beijing, then it may be that the imported or contaminated goods outside Beijing bring in the virus. Therefore, we must carefully comb the sources and channels of new products.
Is salmon the vector of new coronavirus?
Wu Zunyou: Wildlife carrying and imported goods carrying are two different concepts. Civet cats, bats and other wild animals can carry the coronavirus. The virus propagates in their bodies, but they do not get sick. Imported goods carrying means that the workers infected by the new coronavirus pollute these goods when they deal with them. After the contaminated goods are imported into China, others are infected in the process of dealing with them. So wild animals carry virus, and seafood carry virus on the surface after being polluted. In the natural world, there is no coronavirus in fish. But after the fish is caught, because the workers infected with the new crown virus, the surface of the fish may be polluted, and the contaminated seafood is transported to China, and the Chinese workers are infected in the process of treatment, which leads to further human transmission. Of course, this is only a conjecture, which needs to be further confirmed by epidemiological investigation. Under the current situation, it is necessary to do well in the inspection and Quarantine of fresh fruits and vegetables. In particular, two situations need to be noted: