Wu Zunyou introduced, the right side of the chart is the diagnosis report date of the epidemic curve, the left side is the onset of clinical symptoms time statistics, the peak on the 24th. This indicates that the Dalian outbreak was detected relatively early. Many cases were found without clinical symptoms, which suggests that the scale of the epidemic in Dalian is basically locked, there will not be a larger scale cases.

Wu Zunyou introduced, Dalian city more than 100 days without COVID-19 pneumonia cases. Judging from the time, the virus must be from the outside world. Through big data analysis,there is no exact link between the Dalian epidemic and the Beijing epidemic. In addition, through big data analysis, there is no indication that the imported cases are definitively linked to Dalian. It is more likely that it was imported from overseas and that the contaminated seafood was imported.

Wu Zunyou said the similarities between the Beijing outbreak and the Dalian outbreak were related to seafood processing and sales. After the Xinfadi outbreak in Beijing, it was linked to the Wuhan South China Seafood Market, which is also linked to the seafood sales area. All of these scenarios suggest that there is a ***same*** humid and low-temperature environment,which is suitable for the virus to survive. As long as there is contamination, the virus will increasingly congregate locally and will not be easily inactivated, thus posing a risk of transmission in these areas.

The researchers also did some investigations in Beijing and used fluorescent powder in Xinfa Di? A fake virus? did a simulation experiment. This showed that in a polluted environment, some operations, such as cleaning, can lead to workers being infected by aerosols. Employees are infected and then re-contaminate the environment, creating a mixed mode of transmission. In places where seafood is sold and processed, special attention should be paid to prevent COVID-19 pneumonia. Wu Zunyou explained that, first, the current outbreak in Dalian occurred in a workplace and most of the workers were under 60 years old. The infection of COVID-19 pneumonia in this age group is relatively mild. Second, the current outbreak in Dalian was detected in time, and many patients were found before clinical symptoms appeared.

Wu Zunyou mentioned that a reminder to the nation is the need to strengthen testing and management of these environments, especially ventilation. The biggest problem at Wuhan's South China Seafood Market and Beijing's Xinfadi Market is poor ventilation. If the ventilation problem is solved, the risk will be reduced. This seafood processing plant in Dalian also suffers from poor ventilation.