Phylodynamics of SARS-CoV-2 in France, Europe and the world in 2020
- Université Paris Cité and Sorbonne Paris Nord, Inserm, IAME, France
- Collège de France, France
- Sorbonne Université, Inserm, iPLESP, France
- Hôpital Bichat-Claude-Bernard, France
Abstract
Although France was one of the most affected European countries by the COVID-19 pandemic in 2020, the dynamics of SARS-CoV-2 movement within France, but also involving France in Europe and in the world, remain only partially characterized in this timeframe. Here, we analyzed GISAID deposited sequences from 1st January to 31th December 2020 (n = 638,706 sequences at the time of writing). To tackle the challenging number of sequences without the bias of analyzing a single subsample of sequences, we produced 100 subsamples of sequences and related phylogenetic trees from the whole dataset for different geographic scales (worldwide, European countries and French administrative regions) and time periods (from 1st January to 25th July 2020, and from 26th July to 31th December 2020). We applied a maximum likelihood discrete trait phylogeographic method to date exchange events (i.e., a transition from one location to another one), to estimate the geographic spread of SARS-CoV-2 transmissions and lineages into, from and within France, Europe and the world. The results unraveled two different patterns of exchange events between the first and second half of 2020. Throughout the year, Europe was systematically associated with most of the intercontinental exchanges. SARS-CoV-2 was mainly introduced into France from North America and Europe (mostly by Italy, Spain, United Kingdom, Belgium and Germany) during the first European epidemic wave. During the second wave, exchange events were limited to neighboring countries without strong intercontinental movement, but Russia widely exported the virus into Europe during the summer of 2020. France mostly exported B.1 and B.1.160 lineages, respectively during the first and second European epidemic waves. At the level of French administrative regions, the Paris area was the main exporter during the first wave. But, for the second epidemic wave, it equally contributed to virus spread with Lyon area, the second most populated urban area after Paris in France. The main circulating lineages were similarly distributed among the French regions. To conclude, by enabling the inclusion of tens of thousands of viral sequences, this original phylodynamic method enabled us to robustly describe SARS-CoV-2 geographic spread through France, Europe and worldwide in 2020.
Data availability
All genome sequences and associated metadata in the dataset are published in GISAID's EpiCoV database. To view the contributors of each individual sequence with details such as accession number, virus name, collection date, originating lab and submitting lab and the list of authors, visit: https://doi.org/10.55876/gis8.230120zd.All the scripts developed for this study were deposited in the following GitHub repository: https://github.com/Rcoppee/PhyloCoV
Article and author information
Author details
François Blanquart
Antoine Bridier-Nahmias
Funding
No external funding was received for this work.
Copyright
© 2023, Coppée et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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Phylodynamics of SARS-CoV-2 in France, Europe and the world in 2020
eLife 12:e82538.
https://doi.org/10.7554/eLife.82538
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