Reporter : Zhang Ni
Editor : Zhang Kaixin
Publisher : China News Network
Translation, editing : Gan Yung Chyan
/ KUCINTA SETIA
Image : Video Screenshot
In June, the northern hemisphere entered the hot summer. When many people believed that the novel coronavirus (SARS-CoV-2, covi in short) had "disappeared", the covid epidemic suddenly rebounded. The seafood market has repeatedly been hit, and the meat joint factories have frequently "fallen"... Why is the covid epidemic related to these places? People are wondering whether there is a more secret transmission chain for covi.
Image : On 19 June, Beijing residents bought pork. Photo by Jiang Qiming, China News Service
Why are there outbreaks in these places?
Beijing CDC's newly released market sampling results for the new development market show that there are many positive samples in the comprehensive trading hall, especially in the local sales areas of aquatic products and soybean products, and the environmental pollution is relatively heavy.
Another news worth noting is: A week after the case appeared in Beijing, a new local case appeared in Tianjin. The patient has no history of traveling in Beijing. Since 30 May, he has been engaged in dishwashing and occasionally cleaning frozen seafood ingredients.
Almost at the same time, the overseas seafood industry and meat processing factories also exposed many cases of employees collectively infected with covi.
A number of seafood factories in the United States have recently experienced a large number of workers infected with covid. Three seafood workers in the Bristol Bay area of Alaska tested positive for covid. A seafood company in Oregon also experienced an outbreak, with more than 120 employees tested positive.
In South Korea, several employees of the Ministry of Marine and Fisheries in Sejong City have been diagnosed with covid, and the path of infection is not yet clear.
In addition, there is also a recent meat joint factory hit hard by SARS-CoV-2.
The meat processing enterprises in the United States, Germany, the United Kingdom and other places have successively suffered from clustered infections. The number of people infected by a joint meat factory in Germany has risen to more than 700.
Coincidentally, when an outbreak occurred in Wuhan at the end of last year, a large number of confirmed cases also appeared in the Huanan Seafood Market.
In addition, when a French doctor re-tested the nucleic acid sample of a patient last year, he found that a patient with no history of Chinese travel tested positive for covi. This patient is considered to be a French patient "zero", and his identity is a fishmonger.
At present, it is generally accepted in the academic community that fish are almost impossible to become the intermediate host of covi in nature. What exactly caused the epidemic to be inextricably linked to seafood and meat products?
According to some previous epidemiological experts, there are two possibilities: contaminated seafood or meat products are transported to the market through the cold chain logistics to cause the spread, or infected people from the infected area cause the spread.
The survey data also shows that the people infected in Xinfadi Market are relatively concentrated in the aquatic products counter of the beef and mutton hall.
Image : On 13 June, the Beijing Xinfadi wholesale market was temporarily closed, and the police carried out traffic control on the surrounding area. China News Service reporter Zhang Yu photo
Seafood market or just a virus "distribution center"
Analyze the environment in which these epidemic outbreaks occur, almost all are inseparable from the same link-cold chain transportation.
Low temperature is precisely the environment that SARS-CoV-2 likes.
According to the "Public Prevention Guidelines for New Coronavirus Infected Pneumonia" issued by the Chinese Center for Disease Control and Prevention, human coronavirus is more sensitive to heat. As the temperature increases, the resistance of human coronavirus will decline. In a suitable maintenance solution at 4°C, human coronavirus can maintain a moderate stability, and it can be stored for several years in an environment of -60°C.
In China, -18℃ is the national standard recommended for frozen logistics, and also the recommended storage temperature for quick-frozen food and frozen beverages. Some experts believe that the virus's "no fear of cold" feature explains why the virus has been found several times in the seafood market with more refrigerated foods.
WHO officials revealed on 19 June that the gene sequence of the covi strain that appeared in Beijing has been uploaded and shared, showing that it is closely related to the new European coronavirus strain. "There are currently different virus strains spreading, which does not mean that the disease is from Europe, but it is very likely that the virus was imported from outside Beijing."
On the other hand, the epidemic situation has a cluster of infections in the farmers market and meat processing plants, which is also inextricably linked to its own working environment.
"American meat processing plants and some food plants have become hotbeds of viruses. This is because the assembly line process prevents workers from maintaining social distance. To ensure normal processing capacity during the epidemic, workers can only return to work while sick." School of Food Science, China Agricultural University Associate Professor Zhu Yi analyzed in an interview with a reporter from ChinaNews.com.
She emphasized that the outbreak began in the food market, suggesting that the risk is the food industry practitioners in the food processing link. The risks of catching, storing and transporting, trading, slaughtering, washing, cooking, etc. before the entrance are the risks.
Similarly, merchants working in the farmers' market face similar problems. When workers touch contaminated products and rub their noses and rub their eyes, they will be infected, and the dense flow of people in the market has accelerated the spread of the epidemic.
Wu Guizhen, chief expert in biosecurity at the China Center for Disease Control and Secretary of the Party Committee of the Viral Disease Institute, once analyzed that the epidemic rebounded in Beijing and was also a concentrated outbreak in the wholesale market. However, unlike the Huanan Seafood market in Wuhan, the possibility of wild animals causing the epidemic in Beijing is very likely small.
This leaves us with a very important reminder: Is it possible that the source of transmission is an infected person or contaminated food, and the environment of the seafood market has created an opportunity for rapid transmission.
In this way, places like the seafood market may be just a huge virus "transit hub".
Image : On 17 June, inspectors from key areas and key populations in the Beijing Xinfadi Market were tested for new Pneumococcal virus nucleic acid at Fangzhuang Sports Park in Fengtai District. Photo by Jia Tianyong, reporter from China News Service
"Mystery of SARS-CoV-2" is still confusing
Although this epidemic in Beijing has made people's nerves tight again, to some extent, it has also made people's understanding of the virus a step further.
In response to the epidemic in Xinfadi, scientists have recently analyzed a variety of possible transmission routes: the virus is latent in imported frozen foods, and no evolution has occurred due to freezing; the virus is in a dark and humid environment such as the Xinfadi agricultural wholesale market latently, without being disinfected, sterilized, and suddenly exposed to infected people within a certain period of time, resulting in slower evolution, and so on.
The path of virus transmission is a rigorous and complex scientific process, and no conclusion can be made. However, the new site is already reminding people: even if the virus trajectory is still confusing, but the prevention and control network must be prepared.
After the outbreak of in Xinfadi Market in Beijing, the agricultural product market became a new target for epidemic prevention and control across the country almost overnight. Large-scale investigations were quickly launched, nucleic acid testing of market practitioners and sampling of the market environment were screened. check.
At the same time, "foreign defense input" must not only guard people, but also keep an eye on the goods.
In response to the recent cluster infections in Beijing, the General Administration of Customs has deployed the national customs for fresh cold chain products from high-risk countries or regions, such as aquatic products, meat, frozen vegetables, aquatic animals, short-term or low-temperature transportation Imported commodities such as industrial products were monitored for covi risks.
In addition, since 17 June, China Customs has also suspended the export of products from a German pork slaughtering and division and refrigeration company.
For individuals, although there is no evidence of infection by eating food (including seafood products), the Chinese Center for Disease Control has recommended that in order to reduce the possible risks, people should not contact raw fish when buying food.
The concealment of covi's hiding place and the tenacity of vitality continue to exceed people's existing cognition. For humans, understanding SARS-CoV-2 may be destined to be a headwind.
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