Epidemic clues: cough, sneeze and North American pig head! Solve the mystery: multiple related epidemics have been solved!

Recently, eight people infected with the new crown pneumonia virus appeared in the Wanhaixuan community in Dongjiang Port District, Tianjin. In response to this epidemic, Tianjin held a new crown epidemic press conference to "develop the mystery."

The person who announced the virus retrospective results of the community was "Tianjin Sherlock Holmes"-Zhang Ying, deputy director of the Tianjin Center for Disease Control and Prevention, who had been on fire as early as the end of February this year.

After a video investigation, it was finally found that the first case of Wang, who tested positive for the new coronavirus nucleic acid, did not wear a mask in the elevator, and coughed and sneezed, which eventually caused the virus to spread in the community.

Two communication chains in Haixuan District

In Kanhaixuan Community, the epidemic was mainly concentrated in Building 4 and Building 19. Among them, Building 4 was the first building where Wang Mou, who was tested positive for the new coronavirus nucleic acid in Kanhaixuan Community, lived. 4 infected persons.

In addition, 4 infected persons also appeared in Building 19, which has nothing to do with the new coronavirus infection.

Analysis of Infection Chain in Building 4 of Kanhaixuan Community

On November 9, the company of the infected person Wang organized him to carry out a nucleic acid test. In the morning, Wang first entered the elevator of Building 4. He did not wear a mask in the elevator and was still coughing inside.

Less than two minutes after him, one minute and 55 seconds, Kang's family of three walked into the elevator. Coughing will produce droplets. The droplets will settle in the air for a long time, but the droplets will not settle for more than 1 minute. After such a short period of time, when a Kang family enters the elevator, there may be aerosols and The droplets that did not settle caused Kang's infection.

The more critical detail here is that Kang did not wear a mask. If Kang was wearing a mask at that time, this situation might prevent him from being infected and the probability of infection would decrease. Unfortunately, Kang did not wear it when he entered the elevator. Of masks. The epidemiological connection between Kang and Wang is connected.

How is the communication between Building 4 and Building 19 related?

Through epidemiological investigations, it was found that there was a crossing of people in Building 9. In Building 9, there were co-workers of the infected person Wang in Building 4 and colleagues of Shen who worked in Building 19.

Public security officers and disease control personnel have been awake for two consecutive nights, and finally found a clue: Wang Mou, the first infected person found in Building 4, went to visit him on the night of November 9, and he went to look for him in Building 9 colleague. Not only did he stop by, he also made small movements in the elevator, not only coughing, but also sneezing, without wearing a mask.

On November 10th, Shen took the elevator to the 9th building to find his colleague, and then returned to the 19th building. On the afternoon of the 10th, Shen's colleague who lived in the 9th building had dinner in the 19th building.

According to testing, the sample of the elevator surface in Building 9 tested positive for the new coronavirus nucleic acid, and it was positive at multiple points.

Analysis of Infection Chain in Building 19 of Kanhaixuan Community

Shen’s colleague who lives in Building 9 travels back and forth between Building 19 and Building 10. Because this is Shen’s boss, and his company is located in Building 19, it is likely that his hands may be contaminated or otherwise. The pollution mechanically brought the virus to Building 19, and at the same time, Shen himself kept going back and forth between Building 9 and Building 19.

Based on the current clues, the hypothesis of the infection association between Building 4 and Building 19 is proposed-this epidemic is not a direct human-to-human transmission, but the spread of the virus between the two buildings caused by environmental pollution (elevators, building door handles) .

Hailian Cold Storage

Different from Kanhaixuan epidemic virus genotype

Zhang Ying, deputy director of the Tianjin Center for Disease Control and Prevention, also pointed out that there is no connection between the Hailian cold storage epidemic and the Kanhaixuan epidemic because the two viruses are not genetically identical. Hailian cold storage epidemic virus gene is L genotype European family branch Ⅱ, Kanhaixuan epidemic virus gene is L genotype European family branch Ⅰ.

Then, what is the source of infection in Hailian Cold Storage?

Zhang Ying analyzed that on November 7th, we received a notification from Dezhou City, Shandong Province that a batch of imported pork knuckles transferred from Tianjin Port to them tested positive for nucleic acid in the outer packaging. Then, according to this line, Tianjin The Health Commission conducted a full investigation on the Hailian Cold Storage and found Case No. 138 and Case No. 139.

Case 138 is a mover, and the unloaded goods are pork knuckles from Germany.

Case 139 was the driver who transported goods. He transported North American pig heads, but he had never transported German pork knuckle.

According to the current research, the two did not know each other, and there was no intersection. In addition, the pork knuckles are stored in cold storage No. 4, and the pig heads are transported away at gate 6. There is no intersection between the two items.

Further epidemiological investigations were carried out and the monitoring in the cold storage was called, and finally the main reason for the infection of Case 139 was identified.

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November 4 was the storage date of Hailian Cold Storage. Three batches of goods were shipped to Hailian Cold Storage at different times on that day. One batch was German pork knuckle and the other two were North American pig heads.

A key person in this is Case 138 (the unloading worker). He unloaded the pig knuckles into the warehouse, and he also unloaded the pig heads into the warehouse 2, but he did not have the pig heads into the warehouse 5. Carry out unloading.

November 5 was the day when three batches of goods were shipped out of the warehouse, and German pork knuckles were shipped from the operation platform of warehouse 4. Case 138 (handling worker), after moving the pig's head in No. 2 warehouse, the next day he wore the same clothes and the same gloves without disinfection, and continued to leave the warehouse. It is possible that the positive test on the outer packaging of Shandong Dezhou pig knuckles was caused by the contamination of the clothes or gloves of Case 138 (handler).

Truck drivers who are not involved in the removal of pigs

How did he get infected?

The truck driver, case 139, did not participate in the transportation of pig heads during the entire transportation process. How did he get infected?

After the video was retrieved, it turned out that the outer packaging of the pig's head was scattered during the process of leaving the warehouse, and the pig's head with a layer of plastic film rolled to the ground. The driver participated in picking up the pig's head, so he was exposed. This can explain it.139 The source of his infection in case No. 2 was also pig head.

There is also evidence that samples were collected in places where pig heads were scattered. The nucleic acid test was positive, and the sequencing was completely consistent with the genetic sequencing of cases 138 and 139.

From this, it can be confirmed that the source of infection in this incident was North American pig heads, which contaminated pig knuckles in Germany and caused positive pork knuckle packaging; case 138 participated in the removal of pig heads, case 139 participated in the removal of pig heads, and two people were infected . In addition, the three-bed sheets of the porter's resting place were also tested positive for the new coronavirus nucleic acid, which can basically be confirmed and closed.

Video clips of the conference

In addition to the two cases mentioned above, it is not uncommon for the two confirmed cases in Shanghai on November 9th to be ruled out of the possibility of "human-to-human transmission" because they were jointly exposed to the aviation container returning to Shanghai from North America. The container is a closed container with a large amount of shock-absorbing foam, and the internal environment is humid. When cleaning up, neither of them wore masks.

As well as many imported frozen foods and outer packagings, and cold storage door handles this year, live new coronaviruses have been detected.

Looking at the inside of the elevator involved in the Haixuan community, until the prevention and control personnel arrive, the "multi-point positive" can still be detected... How much has the activity of the virus declined during the period from the departure of the confirmed case to the test? Temporarily become a mystery.

Wu Zunyou interpretation:

"Transfer from person to person" may detonate an epidemic

The recent epidemic has made everyone think that, on the surface, the new coronavirus can be transmitted from person to person. In this regard, Wu Zunyou, the chief epidemiologist of the China Centers for Disease Control and Prevention, said that from the appearance it seems to be "person-to-person transmission", but in fact it still has not left the mode of transmission of respiratory infectious diseases, that is, "contact transmission."

With regard to contact transmission, the more common understanding is that patients and healthy people shake hands, or touch the handles together (the new coronavirus will spread).

Now, through the cold chain, including the contaminated empty containers just reported by Shanghai, transmission can be caused by contact. Among them, aviation container and cold chain food actually play a "carrier" role.

During the COVID-19 pandemic, the role of asymptomatic infected persons is very limited. However, when the epidemic is controlled, in the absence of an epidemic, asymptomatic infected persons play a very important role in detonating an epidemic from zero to one.

Wu Zunyou said that in the summer, we believe that the new crown virus does not distinguish between winter and summer, but in fact its epidemic in winter will be more serious. From the perspective of the global epidemic situation, entering the early winter, especially after November, the number of new cases reported every day in the world often exceeds 600,000 per day, and the number of cases has broken the record many times.

In the past few days, sporadic cases in many places in the country also indicate that the new crown virus is constantly beating on the country, and this winter is facing a big test.

First of all, you must insist on wearing a mask. This winter, when you enter a confined space like an elevator, you must wear a mask.

Second, after returning home from a public place, the first thing is to disinfect the hands.

Third, pay attention to hygiene and etiquette and don't spit on the spot.