论文标题
跟踪SARS-COV-2流行期间的繁殖数和锁定效果的时间过程：非参数估计
Tracking the time course of reproduction number and lockdown's effect during SARS-CoV-2 epidemic: nonparametric estimation
论文作者
论文摘要
锁定对SARS-COV-2流行进化的准确建模是一个关键问题，例如告知有关紧急管理的医疗保健决定。到目前为止，隔室和空间模型使用接触率的参数描述，通常会假设锁定的时间存在效果。在本文中，我们表明这些假设可能会导致对正在进行的大流行的错误评估。因此，我们开发了一类新的非参数隔室模型，能够描述锁定的影响如何随时间变化。利用正则化理论，住院的数据被映射到无限维空间中，因此获得了一个功能，该功能还考虑了社会疏远的措施和人们对感染风险随着时间的流逝而不断增长的认识。这允许重建SARS-COV-2繁殖编号的连续时间概况，并以前从未达成。当应用于伦巴第（Lombardy）收集的数据时，意大利地区受影响最大的地区，我们的模型说明了人们在限制期间的行为如何变化及其对遏制流行病的重要性。结果还表明，在锁定结束时，伦巴第约12％的人和意大利的5％受SARS-COV-2影响。然后，我们讨论锁定结束后情况如何发展，表明由于假期而在最后几周危险地增加了危险的增加，尤其是在年轻人的人群和增加的移民到达，在2020年8月1日达到大于一个的价值。由于几个国家仍然观察到包括越来越多的流行病，包括意大利在内的流行病，以及在夏天的第二波中，既可以在夏天的范围内进行培养，又可以追求拟议的培养方法，而拟议的方法是拟议的，拟议的方法学是既有的，供应的方法都可以启用，该方法是拟议的，既有又可以启用了苏格尔的范围，否则既有又有的范围，又可以启用苏格德的范围。 SARS-COV-2扩散或评估锁定限制对包含扩散的影响。
Accurate modeling of lockdown effects on SARS-CoV-2 epidemic evolution is a key issue in order e.g. to inform health-care decisions on emergency management. The compartmental and spatial models so far proposed use parametric descriptions of the contact rate, often assuming a time-invariant effect of the lockdown. In this paper we show that these assumptions may lead to erroneous evaluations on the ongoing pandemic. Thus, we develop a new class of nonparametric compartmental models able to describe how the impact of the lockdown varies in time. Exploiting regularization theory, hospitalized data are mapped into an infinite-dimensional space, hence obtaining a function which takes into account also how social distancing measures and people's growing awareness of infection's risk evolves as time progresses. This permits to reconstruct a continuous-time profile of SARS-CoV-2 reproduction number with a resolution never reached before. When applied to data collected in Lombardy, the most affected Italian region, our model illustrates how people behaviour changed during the restrictions and its importance to contain the epidemic. Results also indicate that, at the end of the lockdown, around 12% of people in Lombardy and 5% in Italy was affected by SARS-CoV-2. Then, we discuss how the situation evolved after the end of the lockdown showing that the reproduction number is dangerously increasing in the last weeks due to holiday relax especially in the younger population and increased migrants arrival, reaching values larger than one on August 1, 2020. Since several countries still observe a growing epidemic, including Italy, and all could be subject to a second wave after the summer, the proposed reproduction number tracking methodology can be of great help to health care authorities to prevent another SARS-CoV-2 diffusion or to assess the impact of lockdown restrictions to contain the spread.
