Transmission Dynamics of Coronavirus Disease 2019 (COVID-19) in the World: The Roles of Intervention and Seasonality
Authors: Huang Shunxiang , Wu Lin , Xu Li , Zhang Aihong , Sheng Li , Liu Feng , Zhou Long , Li Jing , Hao Rongzhang , Qian Hua , Fang Sheng , Wang Zhongyi , Li Yingru , Li Yuguo , Lu Chan , Deng Qihong 
Published: July 2020

The coronavirus disease 2019 (COVID-19) is spreading rapidly all over the world. The transmission dynamics of the COVID-19 pandemic is still unclear, but developing strategies for mitigating the severity of the pandemic is yet a top priority for global public health. In this study, we developed a novel compartmental model, SEIR-CV(susceptible-exposed-infectious-removed with control variables), which not only considers the key characteristics of asymptomatic infection and the effects of seasonal variations, but also incorporates different control measures for multiple transmission routes, so as to accurately predict and effectively control the spread of COVID-19. Based on SEIR-CV, we predicted the COVID-19 epidemic situation in China out of Hubei province and proposed corresponding control strategies. The results showed that the prediction results are highly consistent with the outbreak surveillance data, which proved that the proposed control strategies have achieved sound consequent in the actual epidemic control. Subsequently, we have conducted a rolling prediction for the United States, Brazil, India, five European countries (the United Kingdom, Italy, Spain, Germany, and France), southern hemisphere, northern hemisphere, and the world out of China. The results indicate that control measures and seasonal variations have a great impact on the progress of the COVID-19 pandemic. Our prediction results show that the COVID-19 pandemic is developing more rapidly due to the impact of the cold season in the southern hemisphere countries such as Brazil. While the development of the pandemic should have gradually weakened in the northern hemisphere countries with the arrival of the warm season, instead of still developing rapidly due to the relative loose control measures such as the United States and India. Furthermore, the prediction results illustrate that if keeping the current control measures in the main COVID-19 epidemic countries, the pandemic will not be contained and the situation may eventually turn to group immunization, which would lead to the extremely severe disaster of about 5 billion infections and 300 million deaths globally. However, if China’s super stringent control measures were implemented from 15 July, 15 August or 15 September 2020, the total infections would be contained about 15 million, 32 million or 370 million respectively, which indicates that the stringent and timely control measures is critical, and the best window period is before September for eventually overcoming COVID-19.

Significance

COVID-19 is now posing a huge threat to global public health. The key features such as asymptomatic infection and droplet or airborne transmission make COVID-19 more easily spread and more widely distributed around the world. It is an urgent need to explore the optimal intervention strategies and measures to contain the pandemic. Our novel SEIR-CV compartmental model considers the new features of COVID-19, exhibits the impact of the intervention strategies and seasonal variations, and thus can accurately predicts its trajectory in China and the rest of the world. Our research results suggest that control measures and seasonal variations have a great impact on the development of the COVID-19 pandemic, which can only be contained by stringent strategies during the best window period before September 2020 for eventually overcoming COVID-19, otherwise it would cause a severer global catastrophe.