The silence that lasts 56 days, be broken by “west city big ye”.
On June 11, A 52-year-old confirmed case from Xicheng was reported in Beijing after 56 consecutive days with no new confirmed cases reported locally.
More than 200 cases have been confirmed in Beijing in the past 10 days.
After two months, why is Novel Coronavirus making a comeback?
Why did the cluster of infections in Wuhan and Beijing begin in the seafood market?
Does this open a second opportunity to explore the novel Coronavirus source?
National experts 3 into xinfa
A minibus started operation at around 8 PM at the South area of the China Center for Disease Control and Prevention virus Disease Center, located at 100 Yingxin Street, Xicheng District, Beijing, China, June 17, 2007.
Wu Guizhen, chief biosecurity expert at the Chinese Center for Disease Control and Prevention and party secretary of the Institute of Viral Diseases, led a group of people in a hurried car to xinfadi wholesale market, the epicenter of the outbreak.
A report on the website of the Central Commission for Discipline Inspection (CCDI) reproduces the image.
Ten days earlier, on June 11, Beijing reported one new local case, breaking a nearly two-month record of zero new cases.
On the evening of June 12, the China Center for Disease Control and Prevention dispatched eight experts in the fields of epidemiology and infectious disease prevention and control to the national Health Commission.
Why are new cases emerging after nearly two months of “zero new cases”?
Why take place in Xinfadi such a wholesale market again?
A series of questions waiting for them to answer.
According to the above report, experts from the CDC entered xinfadi wholesale market for agricultural products three times on June 14, 15 and 17.
For the first time, more than 200 samples were collected, among which many novel Coronavirus nucleic acid positive samples were detected.
A second time, more than 200 samples were taken from other areas, many of them positive.
The third time, the market water, fish breeding water preservation water, canals, groundwater and other water systems to collect and test.
“In the market environment sampling in Xinfadi, there are more positive samples on the comprehensive trading floor, especially in the local selling areas of aquatic products and soybean products, and the environmental pollution is heavy.”
At a press conference on CoVID-19 prevention and control in Beijing on June 19, Pang Xinghuo, deputy director of the Beijing Center for Disease Control and Prevention, announced the results of sampling.
Positive environmental samples can help researchers restore the “crime scene”, and identify the scope of infection and even the source of infection.
“Different positive samples point to different conclusions: it may point to the environment and the animal or object inside it as the source of infection, or to the person infected by a novel Coronavirus.”
‘For example, if a positive sample is found in an unopened frozen product, it further confirms the possibility of transmission of the virus through the cold chain to the market,’ said Liu Jun, assistant director of the China Center for Disease Control and Prevention and deputy director of the National Influenza Center.
However, if the frozen product is opened after, which suggests that the product may have been touched before, then the conclusion is different.
From person to person or from thing to thing?
For now, both possibilities exist.
Experts tend to think that novel Coronavirus from outside Beijing brought you to Xinfa, a sprawling wholesale produce market.
“It did not originate in Beijing. Someone or something from outside Beijing must have brought the virus to xinfa.”
On June 19, the ninth day in a row that Beijing reported new confirmed cases in China, Wu Zunyou, chief epidemiologist of China CDC, revealed in an interview with CCTV the latest judgment on the novel Coronavirus tracing from Xinfa.
But it is not clear who or what brought the virus to the new site.
Wu Zunyou analysis said that if it is an item, the most likely temperature is lower, frozen items, the virus survival time is relatively long.
If it is a person, it is most likely to fall into two categories. One is a person working in the market who has been to the epidemic area in late May or early June and was infected with an infected person with atypical or asymptomatic symptoms after novel Coronavirus, and then returned to the market after returning to work, which would cause market pollution and spread between people.
The first is that people from areas where imported cases are endemic go shopping in the New Territories, which may pollute the environment and spread infection among workers.
An informal statement from Gao Fu, director of China’s Center for Disease Control and Prevention, suggested another possibility.
On June 16, the National Committee of the Chinese People’s Political Consultative Conference (CPPCC) in Shanghai conducted research on improving the epidemic prevention and control mechanism.
At the research meeting, Gao Fu’s speech quickly became a hot search on Weibo.
“Novel Coronavirus”, he said, “will lurk in a dark, humid, polluted or toxic environment and suddenly expose itself to many people at a certain time.”
Beijing this time is probably not the end of May or early June, it is likely to be postponed a month in advance, there have been a lot of asymptomatic infection or mild patients, so that the environment can be so much virus.
Does this mean that novel Coronavirus has been novel coronavirus among the crowd since April with a latent chain of transmission?
How to find these asymptomatic infected persons?
Since then, the CDC has not made any explanation and response.
Wu zunyou said in an interview with CCTV that the next focus of the investigation will focus on the onset of the earliest cases in Beijing and push forward the incubation period. During that time, major changes occurred in the market, such as whether people from the imported areas returned to work or went shopping in the market.
Where did the virus come from?
The time for the virus to enter the market is uncertain, but there is a near consensus that the virus comes from an external input, which is supported by viral genome sequence data.
On June 18, “Novel Coronavirus National Science and Technology Resource Service System” was published by China CDC.
Two of the three data are genome sequence data of confirmed cases in Beijing and one is genome sequence data of environmental samples.
The genome sequence data is the virus’s identity code.
By sequencing the whole genome of a novel Coronavirus and then comparing it with the existing novel coronavirus genome sequence using bioinformatics analysis method, the “family relationship” between viruses can be seen.
After examining and comparing the genetic data of the three viruses mentioned above, Dong Yan Jin, a virologist from the University of Hong Kong, believes that the three virus genes are only one or two points different from each other and the differences are very small, indicating that they should come from the same source.
Beijing Center for Disease Control and Prevention Yang Peng said in an interview with the media, through the whole genome sequencing found that the virus came from the Direction of Europe, the preliminary determination is related to the importation.
“However, the European strain does not necessarily mean that the virus came from a European country.”
Wu explained in an interview that the concept of the European strain is broad, such as the analysis of the US virus, which also shows that most of it comes from the European strain.
Most of the Russian cases also originated from the European strain.
“That is to say, tests in our laboratory indicate that the strain originated in Europe, could have come from European countries, could have come from countries in the Americas, which cannot be ruled out.
Further information needs to be gathered to help the judgment.”
An unexpected harvest is that the investigation of epidemic situation in Beijing xinfai market has brought a new clue to the novel Coronavirus transmission mystery.
“We’ve been looking for intermediate hosts in the past when we do virus tracing, and it may be time to re-examine whether the virus came from a wild animal.”
Wu Guizhen was interviewed on the ccDI website.
“The outbreak rebounded in Beijing and was also concentrated in the wholesale market, but unlike the southern seafood market in Wuhan, the risk of wild animals causing the outbreak in Beijing is very small.
This leaves us with a very important hint as to whether the source could be an infected person or contaminated food, and the environment in the seafood market creates an opportunity for rapid spread.”