Abstract: Faced with the new corona virus pneumonia (COVID-19) that began in 2019 spread rapidly, what is the mechanism of its infection and what factors affect it? What role does population migration play in infection? By observing variables in population migration, the key points of prevention and control can be know. The answers to these scientific questions will help prevent the spread from the current epidemic and provide experience for similar epidemic in the future.The first step is to construct a kinetic equation for the new coronavirus.
The increase in the number of infections is proportional to the product terms of the number of susceptible people S(t), the number of infected people I(t) and the transmission medium λ. Based on the infectious disease model, after the theoretical deduction, it is found that under the same transmission medium and medical conditions, the key to the spread of new coronavirus is the contact between infected and susceptible people, and the main channel to increase contact is population migration, especially related to Hubei. After further theoretical reasoning, it is found that vaccination of susceptible population will reduce the number of infections.
The second step is to verify the above-mentioned theoretical inference from experience.Based on the timely big data report of the Baidu epidemic, the number of infected people in each province is obtained. Based on the data of the 1% population sample survey in 2015, the data of population migration variables related to Hubei is obtained, and based on the 2018 China Statistical Yearbook, other control variables is obtained that may affect the number of infected people in each province. Using the general least squares model and empirical proof, it is found that the number of people who moved to each province from Hubei and the number of people who moved to Hubei from each province produced a significant positive effect on the number of infected people in each province. After further research, it is found that the key factor that affects the population of Hubei to migrate to each province is whether the economic situation of the residents is better than that of Hubei Province. The permanent resident population of each province, geographical location and the convenience of transportation to Hubei significantly affect the number of people who migrate to Hubei from other provinces.
From the perspective of population migration variables, how can we prevent and control the epidemic? For the destination of Hubei people's migration, we should focus on the prevention and control in those areas with better economic conditions than in the epidemic areas, such as Guangdong and Zhejiang, which are the first and second choice for people in Hubei to go. For the source of Hubei people's migration, we should focus on prevention and control of those provinces with large populations that are adjacent to Hubei and have extremely convenient transportation with Hubei, which are the main sources of non-local persons in Hubei, such as Henan and Hunan. In addition to reducing the population migration variables related to the epidemic area, the theoretical analysis also find that reducing the contact between the susceptible population and the infected population, weakening the transmission medium, improving the medical level, and vaccinating the susceptible population can also inhibit the spread of the disease.
The theoretical significance of this article lies in timely analyzing the transmission mechanism of new coronavirus. The above theoretical inference is proved empirically: The key to the transmission of it is the contact between the infected and susceptible people and the main channel form of increasing the contact is the population migration,especially related to Hubei. The practical significance of the article is to provide some inspirations for early warning and to prevent current and future epidemic from the perspective of population migration.

Key words: new coronavirus, pneumonia, population migration, COVID-19