Effectiveness of Canadian travel restrictions in reducing burden of SARS-CoV-2 variants of concern

Evaluating travel restriction effectiveness in mitigating infectious disease burden is critical for informing public health policy. Here, we quantify where and when variants of SARS-CoV-2 were introduced into Canada to evaluate the extent to which travel restrictions averted viral introductions and COVID-19 case burden. Our results suggest that, across SARS-CoV-2 variants of concern subject to travel restrictions, at least 281 introductions were prevented, accounting for an averted burden of approximately 44,064 cases. This corresponds to approximately 441 averted hospitalizations, 24 averted deaths, and cost savings to Canadian health care systems of approximately 11.2 million Canadian dollars. Travel restrictions were found to be most effective when implemented rapidly during exponential case growth in the focal source and when global circulation was limited. Our analyses reveal that COVID-19 travel restrictions mitigated case burdens and highlight their value in future pandemic response. Summary COVID-19 travel restrictions against variants worked and were most effective when implemented rapidly and preceding new variants’ wider circulation. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement AM was supported by a Canada Graduate Scholarship Doctoral Award from the Canadian Institutes for Health Research. AM, VM, RLM, and JBJ received funding from the British Columbia Centre for Excellence in HIV/AIDS and Providence Healthcare. MW was supported by funding from the Centers of Excellence for Influenza Research and Response (CEIRR). JBJ was supported by an operating grant from the Canadian Institutes of Health Research Coronavirus Rapid Response Programme grant number 440371 and a Canadian Institutes for Health Research Variant of Concern Grant. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes Viral genome sequences analyzed in this study were sourced from the Global initiative on sharing all influenza data (GISAID) coronavirus (CoV) database and are subject to the GISAID EpiFlu Database Access Agreement. Within this agreement, we cannot distribute data to any third part other than Authorized Users. A full set of all subsampled genome sequence accession IDs is available at GISAID EPI\_SET\_230510yr (doi:10.55876/gis8.230510yr), which serves as the data acknowledgement for all originating and submitting laboratories. Those without GISAID access credentials may retrieve information about all data contributors by either clicking on the DOI or pasting the EPI\_SET ID in the "Data Acknowledgement Locator" on the GISAID homepage. Full and subsampled alignments can be shared to Authorized Users upon request. Scripts used for data curation, inferences, analyses, and visualization are available at github.com/AngMcL/sars-cov-2\_variants_canada. [https://www.github.com/AngMcL/sars-cov-2\_variants\_canada][1] [1]: https://www.github.com/AngMcL/sars-cov-2_variants_canada