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Milwid RM, Gabriele-Rivet V, Ogden NH, Turgeon P, Fazil A, London D, de Montigny S, Rees EE. A methodology for estimating SARS-CoV-2 importation risk by air travel into Canada between July and November 2021. BMC Public Health 2024; 24:1088. [PMID: 38641571 PMCID: PMC11027292 DOI: 10.1186/s12889-024-18563-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2023] [Accepted: 04/09/2024] [Indexed: 04/21/2024] Open
Abstract
BACKGROUND Estimating rates of disease importation by travellers is a key activity to assess both the risk to a country from an infectious disease emerging elsewhere in the world and the effectiveness of border measures. We describe a model used to estimate the number of travellers infected with SARS-CoV-2 into Canadian airports in 2021, and assess the impact of pre-departure testing requirements on importation risk. METHODS A mathematical model estimated the number of essential and non-essential air travellers infected with SARS-CoV-2, with the latter requiring a negative pre-departure test result. The number of travellers arriving infected (i.e. imported cases) depended on air travel volumes, SARS-CoV-2 exposure risk in the departure country, prior infection or vaccine acquired immunity, and, for non-essential travellers, screening from pre-departure molecular testing. Importation risk was estimated weekly from July to November 2021 as the number of imported cases and percent positivity (PP; i.e. imported cases normalised by travel volume). The impact of pre-departure testing was assessed by comparing three scenarios: baseline (pre-departure testing of all non-essential travellers; most probable importation risk given the pre-departure testing requirements), counterfactual scenario 1 (no pre-departure testing of fully vaccinated non-essential travellers), and counterfactual scenario 2 (no pre-departure testing of non-essential travellers). RESULTS In the baseline scenario, weekly imported cases and PP varied over time, ranging from 145 to 539 cases and 0.15 to 0.28%, respectively. Most cases arrived from the USA, Mexico, the United Kingdom, and France. While modelling suggested that essential travellers had a higher weekly PP (0.37 - 0.65%) than non-essential travellers (0.12 - 0.24%), they contributed fewer weekly cases (62 - 154) than non-essential travellers (84 - 398 per week) given their lower travel volume. Pre-departure testing was estimated to reduce imported cases by one third (counterfactual scenario 1) to one half (counterfactual scenario 2). CONCLUSIONS The model results highlighted the weekly variation in importation by traveller group (e.g., reason for travel and country of departure) and enabled a framework for measuring the impact of pre-departure testing requirements. Quantifying the contributors of importation risk through mathematical simulation can support the design of appropriate public health policy on border measures.
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Affiliation(s)
- Rachael M Milwid
- Public Health Risk Sciences Division, National Microbiology Laboratory, Public Health Agency of Canada, St-Hyacinthe, QC, Canada
- Epidemiology of Zoonoses and Public Health Research Unit, Faculté de médecine vétérinaire, Université de Montréal, Saint-Hyacinthe, QC, Canada
| | - Vanessa Gabriele-Rivet
- Public Health Risk Sciences Division, National Microbiology Laboratory, Public Health Agency of Canada, St-Hyacinthe, QC, Canada.
- Epidemiology of Zoonoses and Public Health Research Unit, Faculté de médecine vétérinaire, Université de Montréal, Saint-Hyacinthe, QC, Canada.
| | - Nicholas H Ogden
- Public Health Risk Sciences Division, National Microbiology Laboratory, Public Health Agency of Canada, St-Hyacinthe, QC, Canada
- Department of Pathology and Microbiology, Faculty of Veterinary Medicine, Université de Montréal, Saint-Hyacinthe, QC, Canada
- Epidemiology of Zoonoses and Public Health Research Unit, Faculté de médecine vétérinaire, Université de Montréal, Saint-Hyacinthe, QC, Canada
| | - Patricia Turgeon
- Public Health Risk Sciences Division, National Microbiology Laboratory, Public Health Agency of Canada, St-Hyacinthe, QC, Canada
- Department of Pathology and Microbiology, Faculty of Veterinary Medicine, Université de Montréal, Saint-Hyacinthe, QC, Canada
- Epidemiology of Zoonoses and Public Health Research Unit, Faculté de médecine vétérinaire, Université de Montréal, Saint-Hyacinthe, QC, Canada
| | - Aamir Fazil
- Public Health Risk Sciences Division, National Microbiology Laboratory, Public Health Agency of Canada, Guelph, Guelph, ON, Canada
| | - David London
- Physique Des Particules, Université de Montréal, Faculté Des Arts Et Des Sciences, Montréal, QC, Canada
| | - Simon de Montigny
- Emergency Management Branch, Global Public Health Intelligence Network Tiger Team, Public Health Agency of Canada, Ottawa, ON, Canada
| | - Erin E Rees
- Public Health Risk Sciences Division, National Microbiology Laboratory, Public Health Agency of Canada, St-Hyacinthe, QC, Canada
- Department of Pathology and Microbiology, Faculty of Veterinary Medicine, Université de Montréal, Saint-Hyacinthe, QC, Canada
- Epidemiology of Zoonoses and Public Health Research Unit, Faculté de médecine vétérinaire, Université de Montréal, Saint-Hyacinthe, QC, Canada
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Hurford A, Martignoni MM, Loredo-Osti JC, Anokye F, Arino J, Husain BS, Gaas B, Watmough J. Pandemic modelling for regions implementing an elimination strategy. J Theor Biol 2023; 561:111378. [PMID: 36584747 PMCID: PMC9794400 DOI: 10.1016/j.jtbi.2022.111378] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Revised: 11/15/2022] [Accepted: 11/30/2022] [Indexed: 12/29/2022]
Abstract
During the COVID-19 pandemic, some countries, such as Australia, China, Iceland, New Zealand, Thailand, and Vietnam successfully implemented an elimination strategy, enacting strict border control and periods of lockdowns to end community transmission. Atlantic Canada and Canada's territories implemented similar policies, and reported long periods with no community cases. In Newfoundland and Labrador (NL), Nova Scotia, and Prince Edward Island a median of 80% or more of daily reported cases were travel-related from July 1, 2020 to May 31, 2021. With increasing vaccination coverage, it may be appropriate to exit an elimination strategy, but most existing epidemiological frameworks are applicable only to situations where most cases occur in the community, and are not appropriate for regions that have implemented an elimination strategy. To inform the pandemic response in regions that are implementing an elimination strategy, we extend importation modelling to consider post-arrival travel restrictions, and pharmaceutical and non-pharmaceutical interventions in the local community. We find that shortly after the Omicron variant had begun spreading in Canada, the expected daily number of spillovers, infections spread to NL community members from travellers and their close contacts, was higher than any time previously in the pandemic. By December 24, 2021, the expected number of spillovers was 44% higher than the previous high, which occurred in late July 2021 shortly after travel restrictions were first relaxed. We develop a method to assess the characteristics of potential future community outbreaks in regions that are implementing an elimination strategy. We apply this method to predict the effect of variant and vaccination coverage on the size of hypothetical community outbreaks in Mount Pearl, a suburb of the St. John's metropolitan area in NL. Our methodology can be used to evaluate alternative plans to relax public health restrictions when vaccine coverage is high in regions that have implemented an elimination strategy. This manuscript was submitted as part of a theme issue on "Modelling COVID-19 and Preparedness for Future Pandemics".
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Affiliation(s)
- Amy Hurford
- Memorial University of Newfoundland, Department of Biology, St. John's, NL A1C 5S7, Canada; Memorial University of Newfoundland, Mathematics and Statistics Department, St. John's, NL A1C 5S7, Canada.
| | - Maria M. Martignoni
- Memorial University of Newfoundland, Mathematics and Statistics Department, St. John’s, NL A1C 5S7, Canada
| | - J. Concepción Loredo-Osti
- Memorial University of Newfoundland, Mathematics and Statistics Department, St. John’s, NL A1C 5S7, Canada
| | - Francis Anokye
- Memorial University of Newfoundland, Department of Biology, St. John’s, NL A1C 5S7, Canada
| | - Julien Arino
- University of Manitoba, Department of Mathematics and Data Science Nexus, Winnipeg, MB R3B 2E9, Canada
| | - Bilal Saleh Husain
- University of New Brunswick, Department of Mathematics and Statistics, Fredericton, NB E3B 5A3, Canada
| | - Brian Gaas
- Government of Yukon, Department of Health and Social Services, Whitehorse, YT Y1A 3T8, Canada
| | - James Watmough
- University of New Brunswick, Department of Mathematics and Statistics, Fredericton, NB E3B 5A3, Canada
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Hincapie R, Munoz DA, Ortega N, Isfeld-Kiely HK, Shaw SY, Keynan Y, Rueda ZV. Effect of flight connectivity on the introduction and evolution of the COVID-19 outbreak in Canadian provinces and territories. J Travel Med 2022; 29:6679266. [PMID: 36041018 PMCID: PMC9452173 DOI: 10.1093/jtm/taac100] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/02/2022] [Revised: 08/12/2022] [Accepted: 08/15/2022] [Indexed: 12/30/2022]
Abstract
BACKGROUND The COVID-19 pandemic has challenged health services and governments in Canada and around the world. Our research aims to evaluate the effect of domestic and international air travel patterns on the COVID-19 pandemic in Canadian provinces and territories. METHODS Air travel data were obtained through licensed access to the 'BlueDot Intelligence Platform', BlueDot Inc. Daily provincial and territorial COVID-19 cases for Canada and global figures, including mortality, cases recovered and population data were downloaded from public datasets. The effects of domestic and international air travel and passenger volume on the number of local and non-local infected people in each Canadian province and territory were evaluated with a semi-Markov model. Provinces and territories are grouped into large (>100 000 confirmed COVID-19 cases and >1 000 000 inhabitants) and small jurisdictions (≤100 000 confirmed COVID-19 cases and ≤1 000 000 inhabitants). RESULTS Our results show a clear decline in passenger volumes from March 2020 due to public health policies, interventions and other measures taken to limit or control the spread of COVID-19. As the measures were eased, some provinces and territories saw small increases in passenger volumes, although travel remained below pre-pandemic levels. During the early phase of disease introduction, the burden of illness is determined by the connectivity of jurisdictions. In provinces with a larger population and greater connectivity, the burden of illness is driven by case importation, although local transmission rapidly replaces imported cases as the most important driver of increasing new infections. In smaller jurisdictions, a steep increase in cases is seen after importation, leading to outbreaks within the community. CONCLUSIONS Historical travel volumes, combined with data on an emerging infection, are useful to understand the behaviour of an infectious agent in regions of Canada with different connectivity and population size. Historical travel information is important for public health planning and pandemic resource allocation.
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Affiliation(s)
- Roberto Hincapie
- Escuela de Ingenierias, Universidad Pontificia Bolivariana, Medellin, Colombia
| | - Diego A Munoz
- Escuela de Matemáticas, Universidad Nacional de Colombia, Medellin, Colombia
| | - Nathalia Ortega
- Escuela de Ingenierias, Universidad Pontificia Bolivariana, Medellin, Colombia
| | | | - Souradet Y Shaw
- Department of Community Health Sciences, University of Manitoba, Winnipeg, Canada.,Department of Medical Microbiology and Infectious Diseases, University of Manitoba, Winnipeg, Canada
| | - Yoav Keynan
- National Collaborating Centre for Infectious Diseases, Winnipeg, Canada.,Department of Community Health Sciences, University of Manitoba, Winnipeg, Canada.,Department of Medical Microbiology and Infectious Diseases, University of Manitoba, Winnipeg, Canada.,Department of Internal Medicine, University of Manitoba, Winnipeg, Canada
| | - Zulma Vanessa Rueda
- Department of Medical Microbiology and Infectious Diseases, University of Manitoba, Winnipeg, Canada.,Facultad de Medicina, Universidad Pontificia Bolivariana, Medellin, Colombia
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Choi Y, Zou L, Dresner M. The effects of air transport mobility and global connectivity on viral transmission: Lessons learned from Covid-19 and its variants. TRANSPORT POLICY 2022; 127:22-30. [PMID: 36035455 PMCID: PMC9391984 DOI: 10.1016/j.tranpol.2022.08.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Revised: 07/13/2022] [Accepted: 08/15/2022] [Indexed: 05/12/2023]
Abstract
We investigate the impact of air travel mobility and global connectivity on viral transmission by tracing the announced arrival time of COVID-19 and its major variants in countries around the world. We find that air travel intensity to a country, "effective distance" as measured by international air traffic, is generally a significant predictor for the announced viral arrival time. The level of healthcare infrastructure in a country is less important at predicting the initial transmission and detection time of a virus. A policy variable, notably the percentage reduction of total inbound seats in response to a viral outbreak, is largely ineffective at delaying viral transmission and discovery time. These findings suggest that air network connectivity is a major contributor to the speed of viral transmission. However, government attempts to delay viral transmission by reducing air network connectivity after the virus is first discovered are largely ineffective.
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Affiliation(s)
- Youngran Choi
- David B. O'Maley College of Business, Embry-Riddle Aeronautical University, 1 Aerospace Boulevard, Daytona Beach, FL, 32114, USA
| | - Li Zou
- David B. O'Maley College of Business, Embry-Riddle Aeronautical University, 1 Aerospace Boulevard, Daytona Beach, FL, 32114, USA
| | - Martin Dresner
- Logistics, Business & Public Policy, R.H. Smith School of Business, University of Maryland, College Park, MD, 20742, USA
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Blanford JI, Jong NBD, Schouten SE, Friedrich AW, Araújo-Soares V. Navigating travel in Europe during the pandemic: from mobile apps, certificates and quarantine to traffic-light system. J Travel Med 2022; 29:6520892. [PMID: 35134215 PMCID: PMC9155998 DOI: 10.1093/jtm/taac006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Revised: 12/14/2021] [Accepted: 01/26/2022] [Indexed: 11/21/2022]
Abstract
BACKGROUND Ever since 2020, travelling has become complex, and increasingly so as the COVID-19 pandemic continues. To reopen Europe safely, a consensus of travel measures has been agreed between countries to enable movement between countries with as few restrictions as possible. However, communication of these travel measures and requirements for entry are not always clear and easily available. The aim of this study was to assess the availability, accessibility and harmonization of current travel information available in Europe. METHODS We performed a systematic documental analysis of online publicly available information and synthesized travel entry requirements for all countries in the European Union and Schengen Area (N = 31). For each country we assessed entry requirements, actions after entry, how risk was assessed, and how accessible the information was. RESULTS We found varying measures implemented across Europe for entry and a range of exemptions and restrictions, some of which were consistent between countries. Information was not always easy to find taking on average 10 clicks to locate. Twenty-one countries required pre-travel forms to be completed. Forty apps were in use, 11 serving as digital certification checkers. All countries required some form of COVID-19 certification for entry with some exemptions (e.g. children). Nineteen percent (n = 6) of countries used the ECDC risk assessment system; 80% (n = 25) defined their own. Forty-eight percent (n = 15) of countries used a traffic-light system with 2-5 risk classifications. CONCLUSION A comprehensive set of measures has been developed to enable continued safe travel in Europe. However further refinements and coordination is needed to align travel measures throughout the EU to minimize confusion and maximize adherence to requested measures. We recommend that, along with developing travel measures based on a common set of rules, a standard approach is taken to communicate what these measures are.
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Affiliation(s)
- Justine I Blanford
- Faculty of Geoinformation Science and Earth Observation, University of Twente, Enschede, the Netherlands
| | - Nienke Beerlage-de Jong
- Section of Health Technology and Services Research, Technical Medical Centre, University of Twente, Enschede, the Netherlands
| | - Stephanie E Schouten
- Section of Health Technology and Services Research, Technical Medical Centre, University of Twente, Enschede, the Netherlands
| | - Alex W Friedrich
- Department of Medical Microbiology and Infection Prevention, University Medical Center Groningen, Groningen, the Netherlands
| | - Vera Araújo-Soares
- Section of Health Technology and Services Research, Technical Medical Centre, University of Twente, Enschede, the Netherlands
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McPhee-Knowles S, Hoffman B, Kanary L. The Yukon's experience with COVID-19: Travel restrictions, variants and spread among the unvaccinated. CANADA COMMUNICABLE DISEASE REPORT = RELEVE DES MALADIES TRANSMISSIBLES AU CANADA 2022; 48:17-21. [PMID: 35273465 PMCID: PMC8856720 DOI: 10.14745/ccdr.v48i01a03] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The Yukon's experience with coronavirus disease 2019 (COVID-19) has been an interesting one; the territory successfully implemented travel restrictions to limit importing the virus and rolled out vaccines quickly compared to most Canadian jurisdictions. However, the Yukon's first wave of COVID-19 in June and July 2021 overwhelmed the healthcare system due to widespread transmission in unvaccinated children, youth and adults, despite high vaccination uptake overall and mandatory masking. This experience highlights the importance of continued support for public vaccination programs, widespread vaccine uptake in paediatric populations, and the judicious relaxation of non-pharmaceutical interventions in all Canadian jurisdictions as they reopen while more contagious variants emerge.
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Affiliation(s)
| | - Bryn Hoffman
- Queen’s School of Medicine, Queen’s University, Kingston, ON
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