What are the causes of the outbreaks in Shanghai and Jilin?

1. The source of this round of local epidemic in Shanghai is the environmental pollution caused by the virus (Omicron BA.2 evolutionary branch) carried by imported confirmed cases. Compared with Delta strain, Omicron mutant is more infectious, shorter incubation period, shorter passage time and more difficult to control.

2. This round of local epidemic in Shanghai began on March 1 day, but it was not until the end of March that local residents were brought under large-scale control. On March 28th, Pudong was completely controlled, and on April 28th, several areas in Puxi were 1, which means that the epidemic has spread in the local area for several months before taking control measures, which is also a very important reason for the serious epidemic.

3. Because of the management negligence of Caoxi North Road 1200 (Hua Ting Hotel), it gradually spread, and the internal ventilation system of Hua Ting Hotel was completely built with ventilation pipes, which caused asymptomatic infected people to spread the virus through ventilation pipes. In just ten days, there were 548 asymptomatic infected people, and the number was amazing, but the local epidemic prevention and control measures were not strict at that time.

During the end of April and March, according to the new epidemic notified by the Shanghai Municipal Health and Health Commission, there were thousands of asymptomatic infected people every day, including 5656 asymptomatic infected people in Shanghai on the 29th and 5298 asymptomatic infected people in Shanghai on the 30th. So many asymptomatic infected people in Shanghai are mainly related to the characteristics of Omicron mutant, whose toxicity is relatively weakened and clinical symptoms are relatively mild, which will lead to many infected people having no clinical symptoms after infection.