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

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

Blog Article

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 Time Release 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 Soap/Handcare 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.