双参数广义增长模型在COVID-19中的应用及意义

Application and significance of 2-parameter generalized growth model in COVID-19

摘要:

目的：分析中国、意大利和美国新型冠状病毒肺炎（coronavirus disease 2019，COVID-19）疫情历经的发展阶段及当前疫情所处的情势，为各国疫情的发展趋势提供预测和参考。方法：基于双参数广义增长模型建立COVID-19动力学模型，对中国、意大利和美国累计感染人数分阶段进行非线性拟合，分析各阶段增长模式、感染率及有效再生数Rt，并对中国、意大利和美国累计感染人数进行短期模拟预测分析。中国、意大利和美国拟合数据分别来自中国国家卫生健康委员会及湖北省健康卫生委员会网站每日疫情通报、意大利民事保护部门疫情通报和美国约翰斯·霍普金斯大学实时统计数据。中国疫情数据统计时间段为2020年1月11日至3月3日，意大利、美国疫情数据统计时间段为2020年2月13日至4月25日。结果：根据模型得出，当存在人为干预时，COVID-19累计感染人数不同阶段表现出不同的增长模式，第1阶段呈无障碍指数增长，第2、3阶段呈次指数增长，第4阶段呈次线性增长。中国于2月19日进入第4阶段（p=-1.902 2，Rt=0.970）。截至4月25日，意大利已处于第3阶段（p=0.010 0，Rt=1.001），而美国仍处于第2阶段（p=0.500 5，Rt=1.065）。预测分析结果显示中国第2阶段实际感染人数显著小于预测感染人数，意大利和美国5月10日累计感染人数分别为242 582和1 556 286人。结论：截至4月25日，中国疫情基本得到遏制；意大利疫情得到放缓，但仍然存在蔓延风险；美国疫情处于持续上升阶段，短期不会出现明显回落，且第2阶段将会持续很长时间。

Abstract:

Objective：To analyze the development stages and the current situation of coronavirus disease 2019（COVID-19） in Chi－na，Italy and America，and to provide a forecast and reference for the development trend in each country. Methods：Based on the 2-parameter generalized growth model，the dynamic model of COVID-19 was established，and the cumulative number of infections in China，Italy and America was fitted nonlinearly in each stage. Growth patterns，infection rate and effective reproduction number（Rt） were analyzed. A short-term simulation and prediction analysis were conducted for the cumulative number of infections in China，Italy and the United States. The fitting data for China，Italy and the United States were obtained from the website of National Health Com－mission of PRC and Health Commission of Hubei province，the Italian civil protection department and Johns Hopkins University in the United States，respectively. The statistical data in China is from 11 January to 3 March，Italy and America is from 13 February to 25 April. Results：According to the model，when there is human intervention，the cumulative number of COVID-19 infections shows different growth patterns in different stages. The first stage shows the exponential growth，the second and the third stage show sub-ex－ponential growth，and the fourth stage shows sub-linear growth. China has entered the fourth stage on 19 February（p=-1.902 2，Rt=0.970）. Up to 25 April，Italy is in the third stage（p=0.010 0，Rt=1.001） and America is still in the second stage（p=0.500 5，Rt=1.065）. Predictive analysis shows that the actual number of infections in the second stage in China is significantly lower than the pre－dicted number of infections，and the cumulative number of infections in Italy and America on 10 May will be 242 582 and 1 556 286，respectively. Conclusion：Up to 25 April，the epidemic in China has been basically contained and that in Italy has been slowed down，but there is still a risk of spread. The epidemic situation in the United States is in a sustained upward stage，and there will be no significant fall in a short term. The second stage in the United States will continue for a long time.