Does the second wave of epidemic occur

Yesterday, the world prayed for China, worried about the spread and out of control of China’s new coronavirus. Today’s plot is accelerating. Many countries in the world have seen a sharp rise in cases. Some parts of Italy began to close down (the Italian government has adopted “city closure and isolation” for 11 towns).
Affected by the global epidemic out of control, European and American stock markets suffered “Black Monday”, the Dow Jones index fell by more than 3%. The Nikkei index fell 4.48% in early trading.
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What stage is China in now? Is it the beginning of the end, or the end of the beginning? Even if we can get back to work smoothly? Will the second wave of epidemic happen?
If this is the end of the epidemic, is it right to review every step we have taken since the outbreak in Wuhan? In particular, Wuhan city was closed, and the country adopted a level-1 public health emergency response, nationwide ban on foot, extended holidays, and factory shutdown. Doubts began to grow. Japan and Singapore did not do the same, nor did they seem to have a growing number of views. Let’s go to novel coronavirus pneumonia today to explore the future.
In the early novel coronavirus pneumonia, the epidemic situation in Shanghai was predicted.
Lancaster University published a pessimistic forecast on the epidemic situation in Shanghai on January 24. Without external intervention, there will be more than 900 cases in Shanghai as of February 4 based on R0’s calculation of 3.5 to 4.5. If so, by February 18, the number of cases may reach an astonishing 800000. Even if it is a more optimistic estimate, another Lancet published on January 31 assumes that there are 98 imported cases from Hubei Province in Shanghai. In the case of R0 value of 2.68, the number of patients in Shanghai is predicted to be 80000 by February 18.
The epidemic since the resumption of Wuhan and the fear of the whole country in the dark
Let’s start with how the epidemic happened in Wuhan.
The first case occurred on December 8, 2019 (also known as December 1). By February 24, 2020, there were 64287 confirmed cases in Hubei. That is to say, in a short period of more than two months, from the discovery of the first patient, the amplification was more than 60000 times. How is this done?
Shanghai is a super large city with a population of 30 million. If there are imported cases, what will happen in the future? How should super large cities deal with imported infectious diseases? So far, this issue has been put in front of countries all over the world. Blockade the border? allow someone to continue? After the outbreak, the city will be closed again (such as Wuhan in January and parts of Italy now)?
At the beginning of the outbreak, foreign experts had deep concerns about the national epidemic. As an international city and a hub of domestic transportation and trade, Shanghai has a huge floating population and urban population density, which also makes Shanghai one of the most dangerous domestic cities besides Hubei under the prediction of foreign experts.
For the outbreak of highly infectious infectious diseases, there is always an important feature. If not controlled, the number of diseases will often show an exponential growth trend. One of the important indicators is the R0 value, which is the transmission index. R0 value refers to the average number of people who will infect a certain infectious disease to others without external intervention and without immunity. Simply put, “one patient can infect several people.”. The higher the R0 value, the faster the growth rate.
How terrible is exponential growth? Multiple growth is exponential growth. If we have a large enough paper, the paper thickness will double every time we fold it. If we can fold it 46 times, the paper thickness will reach the distance between the earth and the moon!
The power of exponential growth is enormous.
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At present, experts at home and abroad generally believe that the R0 value of the new coronavirus is between 2.5 and 4.5, that is to say, without intervention, each patient will infect 3-4 new patients, and the new infected will infect more people. Combined with the characteristics of population density and population flow of Shanghai as a super large city, if it is not broken, the result will be chilling.
We’ve just come out of the darkest hour. The battle is not over
In February 24, 2020, novel coronavirus pneumonia clinical group leader Zhang Wenhong and Professor Lu Hongzhou, Secretary of the public health clinical center of Shanghai, issued a presentation on behalf of the Shanghai clinical treatment expert group, and introduced the “answer” of Shanghai in Shanghai. Relevant content was published on medrxiv website in advance and shared with the global community, and discussed with the domestic medical team here.
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In fact, as of February 18, Shanghai has handed over a qualified answer sheet, 333 cases, combining the number of foreign patients and local cases! From February 18 to February 24, there were only two new cases.
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And such a trend chart indicates that Shanghai has won the stage victory in Shanghai’s defense war in the past month under the high consciousness of the government and the public, and has successfully broken and prevented the exponential growth of the new crown epidemic!
Shanghai plan is the epitome of China’s prevention and control war
Shanghai is a city that is most likely to break out and spread in a large area. With the publication of this paper, the Shanghai plan will provide a valuable “Shanghai plan” for the prevention and control of imported sexually transmitted diseases in cities around the world