China officials said that the virus was introduced from Europe and has developed to the stage of human-to-human transmission. COVID-19 Source, the Beijing "new land market" which has attracted much attention, has achieved initial results. Yang Peng, a member of the COVID-19 epidemic prevention and control expert group of Beijing CDC, said in an interview with CCTV News 65438 on June 4th: "The virus comes from Europe, and the initial judgment is related to the input. But how the virus came from is still uncertain. It may be contaminated seafood or meat, or it may be spread by people entering the market through secretions. 」
Guan Yi, director of the State Key Laboratory of Emerging Infectious Diseases of HKU, analyzed in an interview with China Newsweek that there are two possibilities for the Beijing-based cluster epidemic, one is to spread through the cold chain, and the other is for people to enter the market. "But it is most likely to spread through the cold chain. 」
In addition to tracing the source of the virus, Ceng Guang, a member of the National Health Commission Senior Expert Group and the chief scientist of the China Center for Disease Control and Prevention, warned in an interview with Eight Points of Health News that we should focus on the stage of virus transmission: "Now it is no longer a problem of environmental transmission, and the epidemic has progressed to the stage of human-to-human transmission. 」
Ceng Guang suggested that since the market has been closed, the transmission pipeline from the environment to people has been cut off at this stage, and the focus of prevention and control should be shifted to the transmission between people.
Experts suggest strengthening logistics inspection. Yang Zhanqiu, deputy director of the Department of Pathogenic Biology of Wuhan University, said in an interview with the Global Times that the enlightenment of this epidemic to China's prevention and control of COVID-19 lies in: "China has always paid attention to preventing imported infections, ignoring other possible ways of virus transmission, such as imported meat transported through cold chain logistics. Now, it is important to strengthen the inspection and quarantine of imported biological products. 」
According to a report in Medical Science, an expert pointed out that although salmon is not an intermediate host in COVID-19, it may carry virus through environmental pollution, and the virus can survive in a low temperature environment for a long time during frozen transportation. After arriving at Xinfadi market, the ambient temperature rises and the virus is exported.
Monitoring sewers or predicting the outbreak of the epidemic is the most concerned thing for the public: "Where will the epidemic spread and to what extent?" Is there any way to identify the outbreak peak in crowded places as early as possible? According to foreign media reports, many departments in the UK will cooperate to monitor COVID-19 RNA in domestic sewage as an early warning of the epidemic warning system.
In an interview with BBC, Davey Davey Jones, a professor at the School of Natural Sciences of Bangor University in the UK, suggested that analyzing domestic sewage may help researchers predict the extent and scope of the epidemic. In addition to Britain, the United States and the Netherlands are also conducting similar domestic sewage monitoring.
In April, Nature published a study in the Netherlands, saying that researchers can calculate the number of infected people according to the concentration of viral RNA in sewage. Including those latent infections and asymptomatic infections that have not been discovered. "This method may be more effective than large-scale detection. And is relatively cheap and simple. The research team pointed out.