scholarly journals Uncovering two phases of early intercontinental COVID-19 transmission dynamics

2020 ◽  
Vol 27 (8) ◽  
Author(s):  
Jing Yang ◽  
Juan Li ◽  
Shengjie Lai ◽  
Corrine W Ruktanonchai ◽  
Weijia Xing ◽  
...  
Keyword(s):  
Phylogenetic Analyses ◽  
International Travel ◽  
Contact Tracing ◽  
Genetic Sequencing ◽  
Response Strategies ◽  
The World ◽  
Containment Measures ◽  
The Usa ◽  
Community Transmission ◽  
Two Phases

Abstract Background The COVID-19 pandemic has posed an ongoing global crisis, but how the virus spread across the world remains poorly understood. This is of vital importance for informing current and future pandemic response strategies. Methods We performed two independent analyses, travel network-based epidemiological modelling and Bayesian phylogeographic inference, to investigate the intercontinental spread of COVID-19. Results Both approaches revealed two distinct phases of COVID-19 spread by the end of March 2020. In the first phase, COVID-19 largely circulated in China during mid-to-late January 2020 and was interrupted by containment measures in China. In the second and predominant phase extending from late February to mid-March, unrestricted movements between countries outside of China facilitated intercontinental spread, with Europe as a major source. Phylogenetic analyses also revealed that the dominant strains circulating in the USA were introduced from Europe. However, stringent restrictions on international travel across the world since late March have substantially reduced intercontinental transmission. Conclusions Our analyses highlight that heterogeneities in international travel have shaped the spatiotemporal characteristics of the pandemic. Unrestricted travel caused a large number of COVID-19 exportations from Europe to other continents between late February and mid-March, which facilitated the COVID-19 pandemic. Targeted restrictions on international travel from countries with widespread community transmission, together with improved capacity in testing, genetic sequencing and contact tracing, can inform timely strategies for mitigating and containing ongoing and future waves of COVID-19 pandemic.

scholarly journals A Genomic Survey of SARS-CoV-2 Reveals Multiple Introductions into Northern California without a Predominant Lineage

2020 ◽  
Author(s):  
Xianding Deng ◽  
Wei Gu ◽  
Scot Federman ◽  
Louis du Plessis ◽  
Oliver G. Pybus ◽  
...  
Keyword(s):  
Phylogenetic Analyses ◽  
The United States ◽  
Contact Tracing ◽  
Northern California ◽  
Cruise Ship ◽  
Multiple Introductions ◽  
Genomic Epidemiology ◽  
The Usa ◽  
Community Transmission ◽  
Virus Genomes

AbstractThe COVID-19 pandemic caused by the novel coronavirus SARS-CoV-2 has spread globally, resulting in >300,000 reported cases worldwide as of March 21st, 2020. Here we investigate the genetic diversity and genomic epidemiology of SARS-CoV-2 in Northern California using samples from returning travelers, cruise ship passengers, and cases of community transmission with unclear infection sources. Virus genomes were sampled from 29 patients diagnosed with COVID-19 infection from Feb 3rd through Mar 15th. Phylogenetic analyses revealed at least 8 different SARS-CoV-2 lineages, suggesting multiple independent introductions of the virus into the state. Virus genomes from passengers on two consecutive excursions of the Grand Princess cruise ship clustered with those from an established epidemic in Washington State, including the WA1 genome representing the first reported case in the United States on January 19th. We also detected evidence for presumptive transmission of SARS-CoV-2 lineages from one community to another. These findings suggest that cryptic transmission of SARS-CoV-2 in Northern California to date is characterized by multiple transmission chains that originate via distinct introductions from international and interstate travel, rather than widespread community transmission of a single predominant lineage. Rapid testing and contact tracing, social distancing, and travel restrictions are measures that will help to slow SARS-CoV-2 spread in California and other regions of the USA.

scholarly journals COVID-19 Contact Tracing Apps: A Technologic Tower of Babel and the Gap for International Pandemic Control

10.2196/23194 ◽  
2020 ◽  
Vol 8 (11) ◽  
pp. e23194
Author(s):  
Li Du ◽  
Vera Lúcia Raposo ◽  
Meng Wang
Keyword(s):  
Global Health ◽  
International Travel ◽  
Contact Tracing ◽  
Tower Of Babel ◽  
Global Pandemic ◽  
The World ◽  
Legal Barriers ◽  
National Borders

As the world struggles with the new COVID-19 pandemic, contact tracing apps of various types have been adopted in many jurisdictions for combating the spread of the SARS-CoV-2 virus. However, even if they are successful in containing the virus within national borders, these apps are becoming ineffective as international travel is gradually resumed. The problem rests in the plurality of apps and their inability to operate in a synchronized manner, as well as the absence of an international entity with the power to coordinate and analyze the information collected by the disparate apps. The risk of creating a useless Tower of Babel of COVID-19 contact tracing apps is very real, endangering global health. This paper analyzes legal barriers for realizing the interoperability of contact tracing apps and emphasizes the need for developing coordinated solutions to promote safe international travel and global pandemic control.

scholarly journals Implications of a travel connectivity-based approach for infectious disease transmission risks in Oceania

BMJ Open ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. e046206
Author(s):  
Angela Cadavid Restrepo ◽  
Luis Furuya-Kanamori ◽  
Helen Mayfield ◽  
Eric Nilles ◽  
Colleen L Lau
Keyword(s):  
Infectious Disease ◽  
Disease Transmission ◽  
Control Strategies ◽  
Vulnerability Index ◽  
French Polynesia ◽  
International Travel ◽  
Emerging Pathogens ◽  
The World ◽  
The Usa ◽  
The Uk

IntroductionThe increase in international travel brought about by globalisation has enabled the rapid spread of emerging pathogens with epidemic and pandemic potential. While travel connectivity-based assessments may help understand patterns of travel network-mediated epidemics, such approaches are rarely carried out in sufficient detail for Oceania where air travel is the dominant method of transportation between countries.DesignTravel data from the Australian Bureau of Statistics, Stats NZ and the United Nations World Tourism Organization websites were used to calculate travel volumes in 2018 within Oceania and between Oceania and the rest of the world. The Infectious Disease Vulnerability Index (IDVI) was incorporated into the analysis as an indicator of each country’s capacity to contain an outbreak. Travel networks were developed to assess the spread of infectious diseases (1) into and from Oceania, (2) within Oceania and (3) between each of the Pacific Island Countries and Territories (PICTs) and their most connected countries.ResultsOceania was highly connected to countries in Asia, Europe and North America. Australia, New Zealand and several PICTs were highly connected to the USA and the UK (least vulnerable countries for outbreaks based on the IDVI), and to China (intermediate low vulnerable country). High variability was also observed between the PICTs in the geographical distribution of their international connections. The PICTs with the highest number of international connections were Fiji, French Polynesia, Guam and Papua New Guinea.ConclusionTravel connectivity assessments may help to accurately stratify the risk of infectious disease importation and outbreaks in countries depending on disease transmission in other parts of the world. This information is essential to track future requirements for scaling up and targeting outbreak surveillance and control strategies in Oceania.

scholarly journals COVID-19 Contact Tracing Apps: A Technologic Tower of Babel and the Gap for International Pandemic Control (Preprint)

2020 ◽  
Author(s):  
Li Du ◽  
Vera Lúcia Raposo ◽  
Meng Wang
Keyword(s):  
Global Health ◽  
International Travel ◽  
Contact Tracing ◽  
Tower Of Babel ◽  
Global Pandemic ◽  
The World ◽  
Legal Barriers ◽  
National Borders

UNSTRUCTURED As the world struggles with the new COVID-19 pandemic, contact tracing apps of various types have been adopted in many jurisdictions for combating the spread of the SARS-CoV-2 virus. However, even if they are successful in containing the virus within national borders, these apps are becoming ineffective as international travel is gradually resumed. The problem rests in the plurality of apps and their inability to operate in a synchronized manner, as well as the absence of an international entity with the power to coordinate and analyze the information collected by the disparate apps. The risk of creating a useless Tower of Babel of COVID-19 contact tracing apps is very real, endangering global health. This paper analyzes legal barriers for realizing the interoperability of contact tracing apps and emphasizes the need for developing coordinated solutions to promote safe international travel and global pandemic control.

scholarly journals The pandemic predominantly hits poor neighbourhoods? SARS-CoV-2 infections and COVID-19 fatalities in German districts

2020 ◽  
Vol 30 (6) ◽  
pp. 1176-1180 ◽  
Author(s):  
Thomas Plümper ◽  
Eric Neumayer
Keyword(s):  
Social Stratification ◽  
Social Deprivation ◽  
Positive Association ◽  
International Travel ◽  
Second Phase ◽  
Complex Picture ◽  
The Usa ◽  
Precautionary Measures ◽  
Two Phases ◽  
The Uk

Abstract Background Reports from the UK and the USA suggest that coronavirus disease 2019 (COVID-19) predominantly affects poorer neighbourhoods. This article paints a more complex picture by distinguishing between a first and second phase of the pandemic. The initial spread of infections and its correlation with socio-economic factors depends on how the virus first entered a country. The second phase of the pandemic begins when individuals start taking precautionary measures and governments implement lockdowns. In this phase, the spread of the virus depends on the ability of individuals to socially distance themselves, which is to some extent socially stratified. Methods We analyze the geographical distribution of known cumulative cases and fatalities per capita in an ecological analysis across local districts in Germany distinguishing between the first and the second phase of the pandemic. Results In Germany, the virus first entered via individuals returning from skiing in the Alps and other international travel. In this first phase, we find a positive association between the wealth of a district and infection rates and a negative association with indicators of social deprivation. During the second phase and controlling for path dependency, districts with a higher share of university-educated employees record fewer new infections and deaths and richer districts record fewer deaths, districts with a higher unemployment rate record more deaths. Conclusions The social stratification of COVID-19 changes substantively across the two phases of the pandemic in Germany. Only in the second phase and controlling for temporal dependence does COVID-19 predominantly hit poorer districts.

scholarly journals Early intervention is the key to success in COVID-19 control

2020 ◽  
Author(s):  
Rachelle N. Binny ◽  
Michael G. Baker ◽  
Shaun C. Hendy ◽  
Alex James ◽  
Audrey Lustig ◽  
...  
Keyword(s):  
New Zealand ◽  
Process Model ◽  
Peak Load ◽  
Time Frame ◽  
Contact Tracing ◽  
List Type ◽  
Executive Summary ◽  
Response Strategies ◽  
Community Transmission ◽  
At Home

AbstractNew Zealand responded to the COVID-19 pandemic with a combination of border restrictions and an Alert Level system that included strict stay-at-home orders. These interventions were successful in containing the outbreak and ultimately eliminating community transmission of COVID-19. The timing of interventions is crucial to their success. Delaying interventions for too long may both reduce their effectiveness and mean that they need to be maintained for a longer period of time. Here, we use a stochastic branching process model of COVID-19 transmission and control to simulate the epidemic trajectory in New Zealand and the effect of its interventions during its COVID-19 outbreak in March-April 2020. We use the model to calculate key outcomes, including the peak load on the contact tracing system, the total number of reported COVID-19 cases and deaths, and the probability of elimination within a specified time frame. We investigate the sensitivity of these outcomes to variations in the timing of the interventions. We find that a delay to the introduction of Alert Level 4 controls results in considerably worse outcomes. Changes in the timing of border measures have a smaller effect. We conclude that the rapid response in introducing stay-at-home orders was crucial in reducing the number of cases and deaths and increasing the probability of elimination.Executive SummaryEvaluating the effectiveness of New Zealand’s COVID-19 response, relative to hypothetical response scenarios, is important for guiding future response strategies. We assess the importance of early implementation of interventions for controlling COVID-19.We model counterfactual (alternative ‘what-if’) scenarios in which the timings of three policy interventions are varied: border restrictions requiring 14-day quarantine of all international arrivals, border closure except to returning residents and citizens, and Alert Level 4 restrictions.Key measures describing the dynamics of a COVID-19 outbreak (notably peak load on the contact tracing system, the total number of reported COVID-19 cases and deaths, and the probability of elimination within a specified time frame), are used to compare outcomes from each scenario with New Zealand’s actual outcomes.Key measures were more sensitive to the timing of Alert Level 4, than to timing of border restrictions and border closure. Of the three counterfactual scenarios, an earlier start to Alert Level 4 would have resulted in the greatest reduction in numbers of cases and deaths.Delaying the start of Alert Level 4 by 20 days could have led to over 11,500 cases and 200 deaths, and would have substantially reduced the probability of eliminating community transmission of COVID-19, requring a longer period at Alert Level 4 to achieve control.

scholarly journals Introduction and transmission of SARS-CoV-2 B.1.1.7 in Denmark

2021 ◽  
Author(s):  
Thomas Yssing Michaelsen ◽  
Marc Bennedbaek ◽  
Lasse Engbo Christiansen ◽  
Mia Sarah Fischer Jorgensen ◽  
Camilla Holten Moller ◽  
...  
Keyword(s):  
Real Time ◽  
Phylogenetic Analyses ◽  
Contact Tracing ◽  
Epidemic Control ◽  
The World ◽  
Travel Restrictions ◽  
The Face ◽  
Time Test ◽  
Comprehensive Surveillance

In early 2021, the SARS-CoV-2 lineage B.1.1.7 became dominant across large parts of the world. In Denmark, comprehensive and real-time test, contact-tracing, and sequencing efforts were applied to sustain epidemic control. Here, we use these data to investigate the transmissibility, introduction, and onward transmission of B.1.1.7 in Denmark. In a period with stable restrictions, we estimated an increased B.1.1.7 transmissibility of 58% (95% CI: [56%,60%]) relative to other lineages. Epidemiological and phylogenetic analyses revealed that 37% of B.1.1.7 cases were related to the initial introduction in November 2020. Continuous introductions contributed substantially to case numbers, highlighting the benefit of balanced travel restrictions and self-isolation procedures coupled with comprehensive surveillance efforts, to sustain epidemic control in the face of emerging variants.

scholarly journals Estimating the establishment of local transmission and the cryptic phase of the COVID-19 pandemic in the USA

2020 ◽  
Author(s):  
Jessica T. Davis ◽  
Matteo Chinazzi ◽  
Nicola Perra ◽  
Kunpeng Mu ◽  
Ana Pastore y Piontti ◽  
...  
Keyword(s):  
Mainland China ◽  
The United States ◽  
International Travel ◽  
Transmission Model ◽  
Travel Restrictions ◽  
The Usa ◽  
Community Transmission ◽  
Key Driver ◽  
Imported Infections ◽  
Local Transmission

We use a global metapopulation transmission model to study the establishment of sustained and undetected community transmission of the COVID-19 epidemic in the United States. The model is calibrated on international case importations from mainland China and takes into account travel restrictions to and from international destinations. We estimate widespread community transmission of SARS-CoV-2 in February, 2020. Modeling results indicate international travel as the key driver of the introduction of SARS-CoV-2 in the West and East Coast metropolitan areas that could have been seeded as early as late-December, 2019. For most of the continental states the largest contribution of imported infections arrived through domestic travel flows.

scholarly journals Molecular epidemiology of SARS-CoV-2 in Greece reveals low rates of onward virus transmission after lifting of travel restrictions based on risk assessment during summer 2020

2021 ◽  
Author(s):  
Evangelia Georgia Kostaki ◽  
Georgios A. Pavlopoulos ◽  
Kleio-Maria Verrou ◽  
Giannis Ampatziadis-Michailidis ◽  
Vaggelis Harokopos ◽  
...  
Keyword(s):  
Public Health ◽  
Risk Assessment ◽  
Molecular Epidemiology ◽  
Phylogenetic Analyses ◽  
Virus Transmission ◽  
International Travel ◽  
Contact Tracing ◽  
Health Measures ◽  
Travel Restrictions ◽  
The Impact

AbstractMolecular epidemiology has provided an additive value to traditional public health tools by identifying SARS-CoV-2 clusters, or providing evidence that clusters based on virus sequences and contact tracing are highly concordant. Our aim was to infer the levels of virus importation and to estimate the impact of public health measures related to travel restrictions to local transmission in Greece. Our phylogenetic and phylogeographic analyses included 389 SARS-CoV-2 sequences collected during the first 7 months of the pandemic in Greece and a random collection in 5 replicates of 3,000 sequences sampled globally, as well as the best hits to our dataset identified by BLAST. Phylogenetic analyses revealed the presence of 70 genetically distinct viruses identified as independent introductions into Greece. The proportion of imported strains was 41%, 11.5%, and 8.8% during the three periods of sampling, namely, March (no travel restrictions), April to June (strict travel restrictions), and July to September (lifting of travel restrictions based on a thorough risk assessment), respectively. These findings reveal low levels of onward transmission from imported cases during summer and underscore the importance of targeted public health measures that can increase the safety of international travel during a pandemic.

scholarly journals Genomic epidemiology of SARS-CoV-2 spread in Scotland highlights the role of European travel in COVID-19 emergence

2020 ◽  
Author(s):  
Ana da Silva Filipe ◽  
James Shepherd ◽  
Thomas Williams ◽  
Joseph Hughes ◽  
Elihu Aranday-Cortes ◽  
...  
Keyword(s):  
Real Time ◽  
Hospital Admissions ◽  
International Travel ◽  
European Countries ◽  
Added Value ◽  
Contact Tracing ◽  
Genomic Epidemiology ◽  
First Case ◽  
Travel Restrictions ◽  
Community Transmission

AbstractSARS-CoV-2, the causative agent of COVID-19, emerged in Wuhan, China in December 2019 and spread rapidly throughout the world. Understanding the introductions of this new coronavirus in different settings may assist control efforts and the establishment of frameworks to support rapid response in future infectious disease outbreaks.We investigated the first four weeks of emergence of the SARS-CoV-2 virus in Scotland after the first case reported on the 1st March 2020. We obtained full genome sequences from 452 individuals with a laboratory-confirmed diagnosis of COVID-19, representing 20% of all cases until 1st April 2020 (n=2310). This permitted a genomic epidemiology approach to study the introductions and spread of the SARS-2 virus in Scotland.From combined phylogenetic and epidemiological analysis, we estimated at least 113 introductions of SARS-CoV-2 into Scotland during this period. Clusters containing multiple sequences suggestive of onward transmission occurred in 48/86 (56%). 42/86 (51%) clusters had no known international travel history indicating undetected introductions.The majority of viral sequences were most closely related to those circulating in other European countries, including Italy, Austria and Spain. Travel-associated introductions of SARS-CoV-2 into Scotland predated travel restrictions in the UK and other European countries. The first local transmission occurred three days after the first case. A shift from travel-associated to sustained community transmission was apparent after only 11 days. Undetected introductions occurred prior to the first known case of COVID-19. Earlier travel restrictions and quarantine measures might have resulted in fewer introductions into Scotland, thereby reducing the number of cases and the subsequent burden on health services. The high number of introductions and transmission rates were likely to have impacted on national contact tracing efforts. Our results also demonstrate that local real-time genomic epidemiology can be used to monitor transmission clusters and facilitate control efforts to restrict the spread of COVID-19.FundingMRC (MC UU 1201412), UKRI/Wellcome (COG-UK), Wellcome Trust Collaborator Award (206298/Z/17/Z – ARTIC Network; TCW Wellcome Trust Award 204802/Z/16/ZResearch in contextEvidence before this studyCoronavirus disease-2019 (COVID-19) was first diagnosed in Scotland on the 1st of March 2020 following the emergence of the causative severe acute respiratory system coronavirus 2 (SARS-CoV-2) virus in China in December 2019. During the first month of the outbreak in Scotland, 2310 positive cases of COVID-19 were detected, associated with 1832 hospital admissions, 207 intensive care admissions and 126 deaths. The number of introductions into Scotland and the source of those introductions was not known prior to this study.Added value of this studyUsing a combined phylogenetic and epidemiological approach following real-time next generation sequencing of 452 SARS-CoV-2 samples, it was estimated that the virus was introduced to Scotland on at least 113 occasions, mostly from other European countries, including Italy, Austria and Spain. Localised outbreaks occurred in the community across multiple Scottish health boards, within healthcare facilities and an international conference and community transmission was established rapidly, before local and international lockdown measures were introduced.

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