Introduction and transmission of SARS-CoV-2 lineage B.1.1.7, Alpha variant, in Denmark

Thomas Y. Michaelsen, Marc Bennedbæk, Lasse E. Christiansen, Mia S.F. Jørgensen, Camilla H. Møller, Emil A. Sørensen, Simon Knutsson, Jakob Brandt, Thomas B.N. Jensen, Clarisse Chiche-Lapierre, Emilio F. Collados, Trine Sørensen, Celine Petersen, Vang Le-Quy, Mantas Sereika, Frederik T. Hansen, Morten Rasmussen, Jannik Fonager, Søren M. Karst, Rasmus L. MarvigMarc Stegger, Raphael N. Sieber, Robert Skov, Rebecca Legarth, Tyra G. Krause, Anders Fomsgaard, The Danish COVID-19 Genome Consortium (DCGC), Kasper S. Andersen (Member of study group), Martin H. Andersen (Member of study group), Amalie Berg (Member of study group), Susanne R. Bielidt (Member of study group), Sebastian M. Dall (Member of study group), Erika Dvarionaite (Member of study group), Susan H. Hansen (Member of study group), Vibeke R. Jørgensen (Member of study group), Rasmus H. Kirkegaard (Member of study group), Wagma Saei (Member of study group), Trine B. Nicolajsen (Member of study group), Stine K. Østergaard (Member of study group), Rasmus F. Brøndum (Member of study group), Martin Bøgsted (Member of study group), Katja Hose (Member of study group), Tomer Sagi (Member of study group), Miroslaw Pakanec (Member of study group), David Fuglsang-Damgaard (Member of study group), Mette Mølvadgaard (Member of study group), Henrik Krarup (Member of study group), Christina W. Svarrer (Member of study group), Mette T. Christiansen (Member of study group), Anna C. Ingham (Member of study group), Thor B. Johannesen (Member of study group), Martín Basterrechea (Member of study group), Berit Lilje (Member of study group), Kirsten Ellegaard (Member of study group), Povilas Matusevicius (Member of study group), Lars B. Christoffersen (Member of study group), Man Hung E. Tang (Member of study group), Kim L. Ng (Member of study group), Sofie M. Edslev (Member of study group), Sharmin Baig (Member of study group), Ole H. Larsen (Member of study group), Kristian A. Skipper (Member of study group), Søren Vang (Member of study group), Kurt J. Handberg (Member of study group), Marc T.K. Nielsen (Member of study group), Carl M. Kobel (Member of study group), Camilla Andersen (Member of study group), Irene H. Tarpgaard (Member of study group), Svend Ellermann-Eriksen (Member of study group), José A.S. Castruita (Member of study group), Uffe V. Schneider (Member of study group), Nana G. Jacobsen (Member of study group), Christian Andersen (Member of study group), Martin S. Pedersen (Member of study group), Kristian Schønning (Member of study group), Nikolai Kirkby (Member of study group), Lene Nielsen (Member of study group), Line L. Nilsson (Member of study group), Martin B. Friis (Member of study group), Thomas Sundelin (Member of study group), Thomas A. Hansen (Member of study group), Marianne N. Skov (Member of study group), Thomas V. Sydenham (Member of study group), Xiaohui C. Nielsen (Member of study group), Christian H. Schouw (Member of study group), Anders Jensen (Member of study group), Ea S. Marmolin (Member of study group), John E. Coia (Member of study group), Dorte T. Andersen (Member of study group), Mads Albertsen*

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

3 Citations (Scopus)
22 Downloads (Pure)

Abstract

Background: In early 2021, the SARS-CoV-2 lineage B.1.1.7 (Alpha variant) became dominant across large parts of the world. In Denmark, comprehensive and real-time test, contact-tracing, and sequencing efforts were applied to sustain epidemic control. Here, we use these data to investigate the transmissibility, introduction, and onward transmission of B.1.1.7 in Denmark. Methods: We analyzed a comprehensive set of 60,178 SARS-CoV-2 genomes generated from high-throughput sequencing by the Danish COVID-19 Genome Consortium, representing 34% of all positive cases in the period 14 November 2020 to 7 February 2021. We calculated the transmissibility of B.1.1.7 relative to other lineages using Poisson regression. Including all 1976 high-quality B.1.1.7 genomes collected in the study period, we constructed a time-scaled phylogeny, which was coupled with detailed travel history and register data to outline the introduction and onward transmission of B.1.1.7 in Denmark. Results: In a period with unchanged restrictions, we estimated an increased B.1.1.7 transmissibility of 58% (95% CI: [56%, 60%]) relative to other lineages. Epidemiological and phylogenetic analyses revealed that 37% of B.1.1.7 cases were related to the initial introduction in November 2020. The relative number of cases directly linked to introductions varied between 10 and 50% throughout the study period. Conclusions: Our findings corroborate early estimates of increased transmissibility of B.1.1.7. Both substantial early expansion when B.1.1.7 was still unmonitored and continuous foreign introductions contributed considerably to case numbers. Finally, our study highlights the benefit of balanced travel restrictions and self-isolation procedures coupled with comprehensive surveillance efforts, to sustain epidemic control in the face of emerging variants.

Original languageEnglish
Article number47
JournalGenome Medicine
Volume14
Issue number1
ISSN1756-994X
DOIs
Publication statusPublished - 4 May 2022

Bibliographical note

© 2022. The Author(s).

Keywords

  • COVID-19/epidemiology
  • Denmark/epidemiology
  • Humans
  • Phylogeny
  • SARS-CoV-2/genetics

Fingerprint

Dive into the research topics of 'Introduction and transmission of SARS-CoV-2 lineage B.1.1.7, Alpha variant, in Denmark'. Together they form a unique fingerprint.

Cite this