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Original title: A new epidemic may be caused by contaminated imported cold chain food
Recently, an article published jointly by the Beijing Center for Disease Control and Prevention, the Beijing Genomics Institute, the Chinese Academy of Sciences, Tsinghua University, Peking University and other units revealed the latest results. of the investigation on the traceability of the new outbreak in Beijing in June this year, combined with flow analysis and data analysis. , The new outbreak may be caused by the spread of imported food contaminated from the environment to people through cold chain transport.
Newer virus strains can be imported abroad
Following the outbreak of the new outbreak on June 11, the origin of the epidemic has been uncertain. Recently, researchers from the Beijing Municipal Center for Disease Control and Prevention, the Institute of Pathogenic Biology of the Chinese Academy of Medical Sciences, the Beijing Institute of Genomics of the Chinese Academy of Sciences, Tsinghua University and Peking University published a title entitled “Beijing” in the “National Science Review” (National Science Review). The reappearance of the new corona pneumonia epidemic may have its origin in the research article “Food contamination by cold chain as a possible origin of the resurgence of Covid-19 in Beijing.”
The paper used nucleic acid sequencing and viral genome sequence analysis of samples related to the Beijing epidemic in June this year, the environment, and food, combined with extensive epidemiological investigations and big data analysis, revealing that the epidemic may be caused by food contamination from the cold chain. It is proposed that cold chain transport may be a new way of spreading the new coronavirus.
Since the first case of infection was confirmed on June 11, Beijing expanded nucleic acid testing of the virus on 538 employees at the Xinfadi market and found 45 were positive. On June 15, Beijing launched a city-wide nucleic acid detection test. After testing more than 10 million people and 5,342 environmental samples, a total of 368 people were found to be positive for the novel coronavirus nucleic acid. All these infected people are directly or indirectly related to the Xinfadi market: 169 of them are Xinfadi market employees, 103 people have been to the Xinfadi market from May 30 to June 12, and the remaining 96 per capita. Contacts of the above persons. No market-independent early drive chain or independent drive chain was found, suggesting that the newly emerging market is the sole source of the outbreak.
The research team also used the in-house low-viral load sample processing method to perform high-throughput nucleic acid sequencing in 110 cases and environmental samples, and obtained 72 high-quality novel coronavirus genome sequences. The analysis found that all of these sequences have 8 characteristic mutation sites, which have never been found in previous local and imported cases from China. Compared with the new coronavirus gene sequence database, it was found that, in addition to C6026T, there are mainly viruses with 7 other mutation sites in Europe. These results further suggest that the new virus strains can be imported abroad.
The document speculates that the new epidemic may be caused by the transmission of imported food contaminated from the environment to people through cold chain transport. A recent study found that after 21 days of storage at 4 ° C and -20 ° C, the infectivity of the new coronavirus on the surface of chicken, salmon, and pork did not decrease, indicating that chain transport Cold from contaminated food can extend the survival period and spread of the virus.
Stand S14 in the aquatic area can be a source of infection.
The document mentioned that, combined with the epidemiological investigation of the Xinfadi market, the investigators initially determined that booth S14 in the aquatic area at the basement level of the integral trading room (meat and lamb room) may be the source of infection: all 7 staff at booth S14 It is a confirmed case of the new corona and symptoms appear relatively early, neither the employees nor their close contacts have been in the medium / high risk areas of the novel corona pneumonia virus , nor have they had contact with people from these areas.
According to the epidemiological model inferred from the beginning of the epidemic, a total of 5 customers tested positive for the new corona antibody, and these 5 customers have visited booth S14. None of these five clients and their close contacts have visited the medium-high risk area or contacted people in the medium-high risk area in the last 14 days.
The document indicated that further investigation revealed that salmon was the only imported product sold at booth S14.
The newspaper mentioned that the staff analyzed all the salmon in the original sealed package in the cold room outside the Xinfadi market. Of the 3,582 samples, 6 tested positive, 5 of which were from Company X. The company delivered salmon to booth S14 on May 30. By sequencing, 16,341 nucleotides of the novel coronavirus were obtained from a salmon smear from Company X. Analysis found that the tested sequence of this strain included 3 of the 8 mutations in the emerging new virus strain mentioned above. One. Based on the three mutations that have been discovered, the probability that the sample strain from Company X contains 7 or more mutations of the newly emerging epidemic virus strain is inferred to be 60%.
The document mentioned that, although it is not clear if the viral load in salmon is sufficient to cause an infection, the risks of food and environmental contamination still exist. For those countries that have suppressed community transmission, this finding is very important, because the virus can spread again through contaminants transported in the cold chain and can even cause an epidemic. (Dai Xuan) (Dai Xuan)
