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The risk of SARS-CoV-2 outbreaks in low prevalence settings following the removal of travel restrictions

BACKGROUND: Countries around the world have introduced travel restrictions to reduce SARS-CoV-2 transmission. As vaccines are gradually rolled out, attention has turned to when travel restrictions and other non-pharmaceutical interventions (NPIs) can be relaxed. METHODS: Using SARS-CoV-2 as a case s...

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Autores principales: Sachak-Patwa, Rahil, Byrne, Helen M., Dyson, Louise, Thompson, Robin N.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Nature Publishing Group UK 2021
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9053223/
https://www.ncbi.nlm.nih.gov/pubmed/35602220
http://dx.doi.org/10.1038/s43856-021-00038-8
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author Sachak-Patwa, Rahil
Byrne, Helen M.
Dyson, Louise
Thompson, Robin N.
author_facet Sachak-Patwa, Rahil
Byrne, Helen M.
Dyson, Louise
Thompson, Robin N.
author_sort Sachak-Patwa, Rahil
collection PubMed
description BACKGROUND: Countries around the world have introduced travel restrictions to reduce SARS-CoV-2 transmission. As vaccines are gradually rolled out, attention has turned to when travel restrictions and other non-pharmaceutical interventions (NPIs) can be relaxed. METHODS: Using SARS-CoV-2 as a case study, we develop a mathematical branching process model to assess the risk that, following the removal of NPIs, cases arriving in low prevalence settings initiate a local outbreak. Our model accounts for changes in background population immunity due to vaccination. We consider two locations with low prevalence in which the vaccine rollout has progressed quickly – specifically, the Isle of Man (a British crown dependency in the Irish Sea) and the country of Israel. RESULTS: We show that the outbreak risk is unlikely to be eliminated completely when travel restrictions and other NPIs are removed. This general result is the most important finding of this study, rather than exact quantitative outbreak risk estimates in different locations. It holds even once vaccine programmes are completed. Key factors underlying this result are the potential for transmission even following vaccination, incomplete vaccine uptake, and the recent emergence of SARS-CoV-2 variants with increased transmissibility. CONCLUSIONS: Combined, the factors described above suggest that, when travel restrictions are relaxed, it may still be necessary to implement surveillance of incoming passengers to identify infected individuals quickly. This measure, as well as tracing and testing (and/or isolating) contacts of detected infected passengers, remains useful to suppress potential outbreaks while global case numbers are high.
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spelling pubmed-90532232022-05-20 The risk of SARS-CoV-2 outbreaks in low prevalence settings following the removal of travel restrictions Sachak-Patwa, Rahil Byrne, Helen M. Dyson, Louise Thompson, Robin N. Commun Med (Lond) Article BACKGROUND: Countries around the world have introduced travel restrictions to reduce SARS-CoV-2 transmission. As vaccines are gradually rolled out, attention has turned to when travel restrictions and other non-pharmaceutical interventions (NPIs) can be relaxed. METHODS: Using SARS-CoV-2 as a case study, we develop a mathematical branching process model to assess the risk that, following the removal of NPIs, cases arriving in low prevalence settings initiate a local outbreak. Our model accounts for changes in background population immunity due to vaccination. We consider two locations with low prevalence in which the vaccine rollout has progressed quickly – specifically, the Isle of Man (a British crown dependency in the Irish Sea) and the country of Israel. RESULTS: We show that the outbreak risk is unlikely to be eliminated completely when travel restrictions and other NPIs are removed. This general result is the most important finding of this study, rather than exact quantitative outbreak risk estimates in different locations. It holds even once vaccine programmes are completed. Key factors underlying this result are the potential for transmission even following vaccination, incomplete vaccine uptake, and the recent emergence of SARS-CoV-2 variants with increased transmissibility. CONCLUSIONS: Combined, the factors described above suggest that, when travel restrictions are relaxed, it may still be necessary to implement surveillance of incoming passengers to identify infected individuals quickly. This measure, as well as tracing and testing (and/or isolating) contacts of detected infected passengers, remains useful to suppress potential outbreaks while global case numbers are high. Nature Publishing Group UK 2021-10-15 /pmc/articles/PMC9053223/ /pubmed/35602220 http://dx.doi.org/10.1038/s43856-021-00038-8 Text en © The Author(s) 2021 https://creativecommons.org/licenses/by/4.0/Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/ (https://creativecommons.org/licenses/by/4.0/) .
spellingShingle Article
Sachak-Patwa, Rahil
Byrne, Helen M.
Dyson, Louise
Thompson, Robin N.
The risk of SARS-CoV-2 outbreaks in low prevalence settings following the removal of travel restrictions
title The risk of SARS-CoV-2 outbreaks in low prevalence settings following the removal of travel restrictions
title_full The risk of SARS-CoV-2 outbreaks in low prevalence settings following the removal of travel restrictions
title_fullStr The risk of SARS-CoV-2 outbreaks in low prevalence settings following the removal of travel restrictions
title_full_unstemmed The risk of SARS-CoV-2 outbreaks in low prevalence settings following the removal of travel restrictions
title_short The risk of SARS-CoV-2 outbreaks in low prevalence settings following the removal of travel restrictions
title_sort risk of sars-cov-2 outbreaks in low prevalence settings following the removal of travel restrictions
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9053223/
https://www.ncbi.nlm.nih.gov/pubmed/35602220
http://dx.doi.org/10.1038/s43856-021-00038-8
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