基于动态基本再生数的美国新冠肺炎疫情现状评估

COVID-19 assessment of United States based on dynamic basic reproductive number

目的评估美国现阶段新冠肺炎疫情形势,为制定我国的疫情防控策略提供依据。方法基于凤凰网公布的美国新冠肺炎公开数据,计算美国基本再生数(R0)及其动态基本再生数R0(t),评估美国现有防控措施下疫情的传播速率和随时间变化趋势。结果美国的新冠肺炎例确诊病例开始于2020年2月18日,3月6突破单日确诊100例,3月23日突破单日确诊人数10000例,11月12日单日最高病例数为161541例。美国疫情至今的平均基本再生数为1.016[1.015,1.018],最近的7日和14日实时基本再生数为1.044[1.035,1.052]、1.039[1.031,1.047]。动态基本再生数分析显示,美国的基本再生数先上升后下降,最后在1上下波动,并有上升的趋势。灵敏性分析显示,随着序列间隔平均时间的延长,基本再生数随之升高。预测显示美国疫情依旧有反复可能。结论美国的新冠肺炎疫情形势不容乐观,可能将长期存在,增加了我国的输入性风险。

Objective To evaluate the overall situation of COVID-19 in the United States,and to provide a basis for China to make epidemic prevention and control strategies.Methods Based on public data of COVID-19 in the United States collected from IFENG.com,the dynamic trend of the basic reproductive number(R0)in the United States was used to assess the spread rate and trend over time of the epidemic in the United States under the current prevention and control.Results According to public data,the first confirmed COVID-19 case in the United States began on 18 February,2020,with more than 100 confirmed cases on 6 March,10000 confirmed cases on 23 March,and the highest number of confirmed cases on 12 November,was 161541.So far,the overall average basic reproductive number in the US was 1.016[1.015,1.018],and the latest 7-day and 14-day R0(t)were 1.044[1.035,1.052]and 1.039[1.031,1.047].The dynamic basic regeneration number analysis showed that the basic regeneration number of the United States first rise,then fell,and finally fluctuated up and down at 1,and an increasing trend was also observed.Sensitivity analysis showed that the basic regeneration number increased along with the increase of mean time of serial interval.Forecasts based on R0 suggest that the US pandemic is still likely to recur.Conclusion The situation of COVID-19 in the United States is not optimistic and may persist for a long time,which may increase the imported risk to China.