基于再生数的上海市奥密克戎流行趋势研究

Study on the epidemic trend of Omicron in Shanghai based on the reproduction number

目的 基于截至2022年5月9日上海市奥密克戎(Omicron)的流行趋势,估计封控管理之前的早期再生数(R)以及后续的有效再生数(Rt)变化情况。方法 利用指数增长法、最大似然法和下一代矩阵法估计R,利用贝叶斯方法、时依法和新时变法估计Rt。结果 截至2022年3月29日上海市奥密克戎疫情呈指数增长模式。3种方法估计的R值分别为2.36(95%CI:2.33~2.38),2.14(95%CI:2.11~2.18)和2.29(95%CI:2.22~2.38)。结论 R值较大,上海市早期疫情形势较为严峻。自4月7日起,Rt呈下降趋势,表明封控管理措施有效地减缓了疫情增长。Rt的计算方法中,时依法和新时变法可以较快地响应疫情的动态变化趋势;而贝叶斯法反应较为迟缓,且当报告数据波动较大时,会出现分母为0导致无法计算的情况。

Objective To study the epidemic trend of Omicron in Shanghai as of May 9,2022 by estimating the early reproduction number(R)before closed management and the subsequent changes of effective reproduction number(Rt).Methods Exponential growth method,maximum likelihood method and next generation matrix method were used to estimate R,and Bayesian method,Time-Dependent and New Time-Varying were used to estimate Rt.Results As of March 29,2022,the growth of Omicron epidemic in Shanghai followed the exponential growth.The early reproduction number R estimated by three methods was 2.36(95%CI:2.33-2.38),2.14(95%CI:2.11-2.18)and 2.29(95%CI:2.22-2.38),respectively.Conclusion s As the values of R were relatively large,the early epidemic situation in Shanghai was severe.The turning point of the epidemic was on April 7,and the implementation of sealing and control management measures had effectively slowed down the increment of the epidemic cases.Among the methods for calculating the Rt,the Time-Dependent and New Time-Varying can quickly respond to the dynamic trend of the epidemic,while the Bayesian method was relatively slow.Besides,when the reported data fluctuated greatly,the denominator would be zero,thus Rt would be unable to calculate.