Genomic assessment of quarantine measures to prevent SARS-CoV-2 importation and transmission
Dinesh Aggarwal, Andrew J. Page, Ulf Schaefer, George M. Savva, Richard Myers, Erik Volz, Nicholas Ellaby, Steven G. Platt, Natalie Groves, Eileen Gallagher, Niamh Tumelty, Thanh Le-Viet, G. Hughes, Cong Chen, Charlie Turner, Sophie Logan, Abbie Harrison, Cherian Koshy, Amy Ash, Emma L. Wise, Nathan Moore, Matilde Mori, Nick Cortes, Jessica Lynch, Stephen P. Kidd, Derek Fairley, Tanya Curran, James McKenna, Helen Adams, Christophe Fraser, Tanya Golubchik, David Bonsall, Mohammed O. Hassan-Ibrahim, Cassandra S. Malone, Benjamin J. Cogger, Michelle Wantoch, Nicola Reynolds, Ben Warne, Joshua Maksimovic, Karla Spellman, Kathryn McCluggage, John P.T. Mo, Robert Beer, Safiah Afifi, Sian Morgan, Angela Marchbank, Anna Price, Christine Kitchen, Huw Gulliver, Ian Merrick, Joel Southgate, Martyn F. Guest, Robert J. Munn, Trudy Workman, Thomas R. Connor, William Fuller, Catherine Bresner, Luke B. Snell, Amita Patel, Themoula Charalampous, Gaia Nebbia, Rahul Batra, Jonathan Edgeworth, Samuel C. Robson, Angela H. Beckett, David M. Aanensen, Anthony P. Underwood, Corin Yeats, Khalil Abudahab, Ben Taylor, Mirko Menegazzo, Gemma Clark, Wendy Smith, Manjinder Khakh, Vicki M. Fleming, Michelle M. Lister, Hannah C. Howson‐Wells, Louise Berry, Tim Boswell, Amelia Joseph, Iona Willingham, C. Wayne Jones, Christopher W. Holmes, Paul Bird, Thomas Helmer, Karlie Fallon, Julian W. Tang, Veena Raviprakash, Sharon Campbell, Nicola Sheriff, Victoria Blakey, Lesley-Anne Williams, Matthew Loose, Nadine Holmes, Christopher Moore, Matthew Carlile, Victoria Wright, Fei Sang, Johnny Debebe, Francesc Coll
Abstract
Mitigation of SARS-CoV-2 transmission from international travel is a priority. We evaluated the effectiveness of travellers being required to quarantine for 14-days on return to England in Summer 2020. We identified 4,207 travel-related SARS-CoV-2 cases and their contacts, and identified 827 associated SARS-CoV-2 genomes. Overall, quarantine was associated with a lower rate of contacts, and the impact of quarantine was greatest in the 16-20 age-group. 186 SARS-CoV-2 genomes were sufficiently unique to identify travel-related clusters. Fewer genomically-linked cases were observed for index cases who returned from countries with quarantine requirement compared to countries with no quarantine requirement. This difference was explained by fewer importation events per identified genome for these cases, as opposed to fewer onward contacts per case. Overall, our study demonstrates that a 14-day quarantine period reduces, but does not completely eliminate, the onward transmission of imported cases, mainly by dissuading travel to countries with a quarantine requirement.