The goal of this article is to demonstrate the value of a global perspective on pandemics for understanding how global pandemics caused by novel viruses can unfold. Using the example of the 1918 influenza pandemic, two factors that were central to the evolving pattern of global pandemic waves, connectivity and seasonality, are explored. Examples of the influences of these factors on pandemic waves in different locations are presented. Viewing the 1918 pandemic through the lens of compartmental models of infectious diseases, our analysis suggests that connectivity played a dominant role in the initial stages. With the passage of time and the progressive infection and consequent immunization of more and more people, however, the role of seasonality increased in importance, ultimately becoming the driving force behind the emergence of future waves of infection. Implications of these observations for pandemics caused by novel viruses such as the ongoing COVID-19 pandemic are discussed.

中文翻译：

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连通性和季节性：全球视角下的 1918 年流感和 COVID-19 大流行

本文的目的是展示全球流行病观点的价值，以了解由新型病毒引起的全球流行病如何蔓延。以 1918 年流感大流行为例，探讨了对全球大流行浪潮演变模式至关重要的两个因素，即连通性和季节性。举例说明了这些因素对不同地点大流行波的影响。通过传染病的分区模型观察 1918 年的大流行，我们的分析表明，连通性在初始阶段发挥了主导作用。然而，随着时间的推移和越来越多的人的进行性感染和随之而来的免疫接种，季节性的作用变得越来越重要，最终成为未来感染浪潮出现的驱动力。讨论了这些观察结果对由新型病毒引起的大流行病的影响，例如正在进行的 COVID-19 大流行病。