Assessment of Coronavirus Disease 2019 Intervention Strategies in the Nordic Countries Using Genomic Epidemiology

Sebastian Duchene; Leo Featherstone; Birgitte Freiesleben de Blasio; Edward C Holmes; Jon Bohlin; John H O Pettersson

doi:10.1093/ofid/ofab665

Assessment of Coronavirus Disease 2019 Intervention Strategies in the Nordic Countries Using Genomic Epidemiology

Open Forum Infect Dis. 2022 Jan 3;9(3):ofab665. doi: 10.1093/ofid/ofab665. eCollection 2022 Mar.

Authors

Sebastian Duchene¹, Leo Featherstone¹, Birgitte Freiesleben de Blasio^{2

3}, Edward C Holmes⁴, Jon Bohlin², John H O Pettersson^{4

5}

Affiliations

¹ Department of Microbiology and Immunology, The University of Melbourne at The Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia.
² Department of Methods Development and Analytics, Division of Infectious Disease Control and Environmental Health, Norwegian Institute of Public Health, Oslo, Norway.
³ Department of Biostatistics, Oslo Centre for Biostatistics and Epidemiology, Institute of Basic Medical Sciences, University of Oslo, Norway.
⁴ Sydney Institute for Infectious Diseases, School of Life and Environmental Sciences and School of Medical Sciences, the University of Sydney, Sydney, New South Wales, Australia.
⁵ Zoonosis Science Center, Department of Medical Biochemistry and Microbiology, University of Uppsala, Uppsala, Sweden.

Abstract

We explored how the duration, size, and number of virus transmission clusters, defined as country-specific monophyletic groups in a severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) phylogenetic tree, differed among the Nordic countries of Norway, Sweden, Denmark, Finland, and Iceland. Our results suggest that although geographical connectivity, population density, and openness influence the spread and the size of SARS-CoV-2 transmission clusters, the different country-specific intervention strategies had the largest impact. We also found a significant positive association between the size and duration of transmission clusters in the Nordic countries, suggesting that the rapid deployment of contact tracing is a key response measure in reducing virus transmission.

Keywords: COVID-19; Nordic countries; SARS-CoV-2; genomic epidemiology; transmission clusters.