Istituto Zooprofilattico Sperimentale della Sardegna, 07100 Sassari, Italy.
Pandemic Sciences Institute and Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, Nuffield Department for Medicine, University of Oxford, Oxford OX1 2JD, UK.
Viruses. 2023 Jan 18;15(2):277. doi: 10.3390/v15020277.
Understanding how geography and human mobility shape the patterns and spread of infectious diseases such as COVID-19 is key to control future epidemics. An interesting example is provided by the second wave of the COVID-19 epidemic in Europe, which was facilitated by the intense movement of tourists around the Mediterranean coast in summer 2020. The Italian island of Sardinia is a major tourist destination and is widely believed to be the origin of the second Italian wave. In this study, we characterize the genetic variation among SARS-CoV-2 strains circulating in northern Sardinia during the first and second Italian waves using both Illumina and Oxford Nanopore Technologies Next Generation Sequencing methods. Most viruses were placed into a single clade, implying that despite substantial virus inflow, most outbreaks did not spread widely. The second epidemic wave on the island was actually driven by local transmission of a single B.1.177 subclade. Phylogeographic analyses further suggest that those viral strains circulating on the island were not a relevant source for the second epidemic wave in Italy. This result, however, does not rule out the possibility of intense mixing and transmission of the virus among tourists as a major contributor to the second Italian wave.
了解地理和人类流动如何塑造传染病（如 COVID-19）的模式和传播，对于控制未来的疫情至关重要。COVID-19 疫情在欧洲的第二波疫情就是一个有趣的例子，这波疫情是由 2020 年夏季地中海沿岸游客的密集流动所推动的。意大利撒丁岛是一个主要的旅游目的地，人们普遍认为它是意大利第二波疫情的源头。在这项研究中，我们使用 Illumina 和 Oxford Nanopore Technologies 下一代测序方法，对意大利第一波和第二波疫情期间撒丁岛北部流行的 SARS-CoV-2 株的遗传变异进行了特征描述。大多数病毒被归入一个单一的分支，这意味着尽管有大量病毒流入，但大多数疫情并没有广泛传播。岛上的第二波疫情实际上是由单一 B.1.177 亚分支的本地传播驱动的。系统地理学分析进一步表明，岛上流行的这些病毒株并不是意大利第二波疫情的一个相关来源。然而，这一结果并不能排除病毒在游客中大量混合和传播是意大利第二波疫情的一个主要因素。
