1. Sources related to overseas import1February 14 to1February 19, three people infected with the virus imported from abroad appeared in Chaoyang District, Beijing. These virus-infected people may have accidentally infected COVID-19 abroad, but they didn't attack when they were abroad, or they belonged to the kind of virus-infected people who didn't show up, then broke out in China and were finally found. In fact, some imported cases are scattered in big cities like Beijing and Shanghai. After all, there are many foreigners in big cities, many citizens will have more overseas experience than other cities, and foreign measures are not as strict as those in China, so it is understandable that COVID-19 will be infected.

Second, the source of cold chain goods1On February 23rd, an asymptomatic COVID-19 infected person appeared in the new urban area of Beijing, who worked in cold storage. We can infer that this person must have accidentally infected the virus of overseas cold storage items when he was in contact with the cold storage. You know, the virus can survive on the surface of cold storage items for a period of time, and this person is still an asymptomatic infected person, so at least during his work, all cold storage items are contaminated. Sure enough,1From February 23 to 26, there were 9 COVID-19-infected people in Shunyi District, three of whom were related to the cold storage. Although it may not be the cause of the previous infection, it is enough to show that the disinfection problem of cold storage can not be underestimated.

Three, contact with COVID-19 carriers in addition to the three virus-infected people related to the cold storage, the remaining six people should be in contact with COVID-19 carriers to make themselves infected with COVID-19. At this time, the police need to trace the source of COVID-19. And these six people certainly didn't take measures to protect COVID-19, otherwise they wouldn't have accidentally infected COVID-19.