基于接触网络模型和Metropolis-Hastings采样方法的“钻石公主号”新冠肺炎疫情重建

Using the contact network model and Metropolis-Hastings sampling to reconstruct the COVID-19 spread on the “Diamond Princess”

将"钻石公主号"邮轮的新冠肺炎疫情分为无保护和受保护接触的两个阶段,引入更真实地考虑了异质性传播模式的接触网络模型对其进行重建模拟.使用贝叶斯推断结合Metropolis-Hastings采样的方法估计模型的参数,同时使用集合模拟的方式定量评估其不确定性.结果表明,在早期密集交往的情景下,病毒的平均传播率t=0.026,基本再生数R0=6.94,是世卫组织报告的3倍,如此一个月后邮轮上所有的人都会感染病毒.采取了防疫措施以后,t和R0分别降为0.0007和0.2.研究指出除隔离措施外,在封闭空间中采用降低空气中的病毒浓度手段是有用的;高危易感人群必须遵循严格的防护措施以防被病毒侵袭.本研究可为其他邮轮和密闭空间的疫情防护工作提供有价值的启示.

Traditional compartmental models such as SIR(susceptible,infected,recovered)assume that the epidemic transmits in a homogeneous population,but the real contact patterns in epidemics are heterogeneous.Employing a more realistic model that considers heterogeneous contact is consequently necessary.Here,we use a contact network to reconstruct unprotected,protected contact,and airborne spread to simulate the two-stages outbreak of COVID-19(coronavirus disease 2019)on the‘‘Diamond Princess"cruise ship.We employ Bayesian inference and Metropolis-Hastings sampling to estimate the model parameters and quantify the uncertainties by the ensemble simulation technique.During the early epidemic with intensive social contacts,the results reveal that the average transmissibility t was 0.026 and the basic reproductive number R0 was 6.94,triple that in the WHO report,indicating that all people would be infected in one month.The t and R0 decreased to 0.0007 and 0.2 when quarantine was implemented.The reconstruction suggests that diluting the airborne virus concentration in closed settings is useful in addition to isolation,and high-risk susceptible should follow rigorous prevention measures in case exposed.This study can provide useful implications for control and prevention measures for the other cruise ships and closed settings.