The World Health Organization and Chinese experts jointly conducted the Coronary Disease Traceability Investigation Report , which was announced on March 30, focusing on how the 2019 novel coronavirus was transmitted from bats or other animals to humans, and where and when the Coronavirus first came from. Began to spread. The report has a total of 300 pages, and the news update sorted out the contents of the report according to the five questions in everyone’s mind to help you quickly understand the key points.
When will the coronavirus begin to spread?
The first official case in Wuhan was on December 8, 2019. However, according to unpublished government information obtained by the Nanhua Daily, someone may have contracted the disease on November 17.
According to China’s infectious disease information report management system, 174 cases of coronary disease showed symptoms in December. Researchers started from an earlier period of time and found out 76,253 cases of patients with respiratory symptoms in October and November from 233 medical institutions in Wuhan, and then studied and analyzed them in detail. Although 92 cases were considered to be similar to coronary disease infection, after further investigation and evaluation, they were all determined not to be related to coronary disease. Therefore, the expert team believes that the virus is unlikely to have spread in Wuhan in a large amount in these two months.
Although it is impossible to determine when the virus began to spread, the team of experts still tries to understand at what point the virus began to spread widely in the community. According to data provided by China to the WHO, the death rate in Wuhan and pneumonia-related death rates increased rapidly in the third week of 2020, which means that the virus has spread widely among the Wuhan population in the first week of 2020. Hubei Province as a whole did not experience a sharp increase in mortality after one or two weeks later than Wuhan. This also shows that the epidemic first broke out in Wuhan and then spread to the rest of Hubei Province.
Does Coronary Disease originate from the South China Seafood Market?
Experts sequenced the genomes of virus samples from the first few cases and found that eight of them had similar viral genomes, and they were all connected to the South China market. However, there are also many samples of early cases with slightly different genomes, some of which are not related to the South China market. This means that the virus may have spread outside the South China market, and the South China market may be just one of the infected groups.
After the South China Market was closed on January 1, 2020, researchers collected 923 environmental samples from the door, trash cans, toilets, and stalls selling various goods, of which 73 were positive. Most of them came from the sale of seafood, Livestock and poultry stalls. This shows that multiple surfaces in the market were contaminated with the virus at that time, and patients may have contracted the virus from other infected people, animals or products.
The researchers also took samples from 188 animals of 18 different species sold in the market, all of which were negative.
In addition to testing animals in the South China market, the researchers also collected more than 80,000 samples of wild animals, livestock, and poultry from 31 provinces in China. Whether they were before or after the outbreak, these samples were tested for viruses and antibodies. One is positive. Of course, these are just sampling inspections, and it does not mean that there are no viruses in the animals that have not been tested.
Is it possible that the virus originated from a country other than China?
The media reported earlier that Spain took a sample of sewage collected on March 12, 2019, and the result was positive. But apart from this sample, other samples from January 2018 to December 2019 all tested negative.
In order to better understand the virus, many countries also tested the sewage and patient samples collected before the outbreak, and some of them were also positive. The sewage sample collected in Brazil on November 27, 2019 was positive; the sewage sample taken in Italy in mid-December 2019 was positive, and a child in the same district found positive after a throat swab sample taken in early December; France has A sample of a patient with hemoptysis admitted to the hospital on December 27, 2019 was also positive.
These investigations have shown that the virus may have spread before the confirmed cases in these countries, some even earlier than the first case in Wuhan. However, the WHO report pointed out that the results of these reports have not been confirmed, and that only part of the virus genome may be used for testing, and the testing methods used are not uniform. The expert team emphasized that it is still important to investigate these incidents further.
The WHO traceability report also explored the possibility of the virus spreading to the Wuhan market through cold chain videos. Although China caused another wave of epidemics after the domestic epidemic stabilized last year because the imported cold chain products were packaged with viruses, the WHO believes that it would be unusual for the virus to spread in this way before the virus spread widely. . Experts believe that this is also a possibility worthy of further study, especially for exporting cold chain foods to the Wuhan market, where there are bats in the country or exporters of coronavirus samples before the end of 2019.
Is it possible to spread from the laboratory?
The previous U.S. President Trump has repeatedly stated publicly that he believes the virus originated from a Chinese laboratory. The WHO conducted research on this possibility, and pointed out that the Wuhan laboratory did not have a virus similar to coronavirus or a genome capable of forming coronavirus before December 2019. The laboratory staff did not report respiratory symptoms in the weeks or months before December, and their serum did not detect antibodies.
Although the laboratory of the Wuhan Centers for Disease Control and Prevention happened to be moved to a location close to the South China Market on December 2, 2019, there was no problem in the process. They also stated that they had not previously studied any coronaviruses in the laboratory or related to bats. Related viruses.
The WHO’s final conclusion is that the possibility of the virus originating in the laboratory is very low. It is worth mentioning that the WHO conducted research based on the possibility of leaking the virus in the laboratory, and did not consider the possibility of deliberately creating or releasing the virus. The former has ruled out the possibility after other scientists analyzed the genome.
WHO Director-General Tedros Tedros said that although the possibility of laboratory leaks of the virus is considered the most unlikely, further investigations are needed to investigate this possibility.
What are the most likely ways for coronavirus to be transmitted to humans?
The WHO expert team believes that the virus is most likely to be transmitted from bats to humans via another animal. The reason is that the viral genomes in bats are quite different from those of human patients. The evolutionary distance between them is expected to be several decades. The key intermediate host may be missing.
Possible intermediate hosts of the crown disease include mink, pangolin, rabbit, and ferret badger. The panel of experts recommends further research on bats and pangolins in China and Southeast Asia, as well as other wild animals, who are known to have been infected with the virus.