Gallego-García Pilar, Hong Samuel L, Bollen Nena, Dellicour Simon, Baele Guy, Suchard Marc A, Lemey Philippe, Posada David
CINBIO, Universidade de Vigo, Vigo, 36310, Spain.
Galicia Sur Health Research Institute (IIS Galicia Sur), GAS-UVIGO, Pontevedra, Spain.
Commun Med (Lond). 2025 May 30;5(1):209. doi: 10.1038/s43856-025-00912-9.
The spread of SARS-CoV-2 has been influenced by multiple factors, from the inherent transmission capabilities of the different variants to the control measurements put in place. Understanding how new variants enter a country is essential for managing future outbreaks. This study investigates how three major variants-Alpha, Delta, and Omicron (BA.1)-entered Spain and how different restrictions potentially affected their introduction.
We collected Spanish and international SARS-CoV-2 genomes from the GISAID database. Leveraging connectivity data from different countries with Spain, we performed a phylodynamic Bayesian analysis of the SARS-CoV-2 introductions into Spain.
Most introductions of the Alpha variant originated from France. As travel restrictions eased, the number of introductions from different countries increased. During the Delta and Omicron waves, the United Kingdom and Germany became important sources of the virus. The highest number of introductions occurred during the Delta wave, coinciding with fewer travel restrictions and the summer season, when Spain receives a considerable number of tourists.
Our findings highlight the role of international travel in the spread of new variants. They underscore the importance of monitoring travel patterns and implementing targeted public health measures to manage the spread of SARS-CoV-2.
严重急性呼吸综合征冠状病毒2（SARS-CoV-2）的传播受到多种因素影响，从不同变体的内在传播能力到所采取的防控措施。了解新变体如何进入一个国家对于应对未来疫情至关重要。本研究调查了三种主要变体——阿尔法、德尔塔和奥密克戎（BA.1）——如何进入西班牙，以及不同限制措施可能如何影响它们的传入。
我们从全球共享流感数据倡议组织（GISAID）数据库收集了西班牙和国际上的SARS-CoV-2基因组。利用来自不同国家与西班牙的连通性数据，我们对传入西班牙的SARS-CoV-2进行了系统动力学贝叶斯分析。
阿尔法变体的大多数传入源自法国。随着旅行限制放宽，来自不同国家的传入数量增加。在德尔塔和奥密克戎疫情期间，英国和德国成为该病毒的重要来源地。传入数量最多的情况发生在德尔塔疫情期间，这与旅行限制减少以及夏季（此时西班牙接待大量游客）相吻合。
我们的研究结果突出了国际旅行在新变体传播中的作用。它们强调了监测旅行模式以及实施有针对性的公共卫生措施以控制SARS-CoV-2传播的重要性。
