The occurrence of coronavirus disease 2019 (COVID-19) was followed by a small burst of cases around the world; afterward, due to a series of emergency non-pharmaceutical interventions (NPIs), the increasing number of confirmed cases slowed down in many countries. However, the lifting of control measures by the government and the public’s loosening of precautionary behaviors led to a sudden increase in cases, arousing deep concern across the globe. arousing deep concern across the globe. This study evaluates the situation of the COVID-19 pandemic in countries and territories worldwide from January 2020 to February 2021. According to the time-varying reproduction number (R(t)) of each country or territory, the results show that almost half of the countries and territories in the world have never controlled the epidemic. Among the countries and territories that had once contained the occurrence, nearly half failed to maintain their prevention and control, causing the COVID-19 pandemic to rebound across the world—resulting in even higher waves in half of the rebounding countries or territories. This work also proposes and uses a time-varying country-level transmission risk score (CTRS), which takes into account both R(t) and daily new cases, to demonstrate country-level or territory-level transmission potential and trends. Time-varying hierarchical clustering of time-varying CTRS values was used to successfully reveal the countries and territories that contributed to the recent aggravation of the global pandemic in the last quarter of 2020 and the beginning of 2021, and to identify countries and territories with an increasing risk of COVID-19 transmission in the near future. Furthermore, a regression analysis indicated that the introduction and relaxation of NPIs, including workplace closure policies and stay-at-home requirements, appear to be associated with recent global transmission changes. In conclusion, a systematic evaluation of the global COVID-19 pandemic over the past year indicates that the world is now in an unexpected situation, with limited lessons learned. Summarizing the lessons learned could help in designing effective public responses for constraining future waves of COVID-19 worldwide.

2019 年冠状病毒病 (COVID-19) 的发生之后，世界各地出现了少量病例；之后，由于一系列紧急非药物干预措施（NPI），许多国家确诊病例的增长速度放缓。然而，随着政府解除管控措施和民众防范行为松动，导致病例骤增，引发全球高度关注。引起全球的深切关注。本研究评估了 2020 年 1 月至 2021 年 2 月全球各国和地区的 COVID-19 大流行情况。根据时变繁殖数 ( R ( t））每个国家或地区，结果表明，世界上几乎有一半的国家和地区从未控制过疫情。在曾经控制过疫情的国家和地区中，近一半未能保持防控，导致COVID-19大流行在全球范围内反弹，导致有一半反弹的国家或地区波幅更大。这项工作还提出并使用了一个随时间变化的国家级传播风险评分（CTRS），该评分同时考虑了R ( t) 和每日新增病例，以展示国家级或地区级的传播潜力和趋势。使用时变 CTRS 值的时变层次聚类，成功揭示了在 2020 年最后一个季度和 2021 年初导致全球大流行近期恶化的国家和地区，并确定了具有在不久的将来会增加 COVID-19 传播的风险。此外，回归分析表明，NPI 的引入和放宽，包括工作场所关闭政策和居家要求，似乎与最近的全球传播变化有关。总之，对过去一年全球 COVID-19 大流行的系统评估表明，世界现在处于意想不到的境地，吸取的教训有限。总结经验教训可能有助于设计有效的公众应对措施，以限制全球范围内未来的 COVID-19 浪潮。