How the virus arrived in Scotland

Asian traveler with luggage, wearing a face mask and looking at the time table in the departure terminal in an airport during the COVID-19 virus pandemic.

Credit: Kiwis/Getty Images

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus that causes COVID-19, had “multiple introductions” to Scotland in early 2020.

This is according to new research from the Medical Research Council (MRC)-University of Glasgow Centre for Virus Research.

The researchers used the full genome sequences of SARS-CoV-2 to determine the virus was introduced hundreds of times during the first four weeks of the outbreak in Scotland.

This was mainly from European countries like Italy and Spain.

283 introductions

Emma Thomson, Professor of Infectious Diseases at the MRC-University of Glasgow Centre for Virus Research, said:

Our study confirms SARS-CoV-2 entered the Scottish population through at least 283 separate travel-related introductions, leading to multiple clusters of sustained community transmission.

We identified viral lineages with no link to travel as early as three days after the first detection of infection, indicating earlier introduction to Scotland and community spread before the first detected case.

The emergence of continental Europe as the epicentre of the global COVID pandemic was a clear driver of the Scottish outbreak, with the majority of the lineages detected in this study related to European sequences.

Cases with links to China and other countries in South-East Asia were comparatively not detected.

Tracking the new coronavirus to inform policy

Thomson says the speed at which the virus took hold in Scotland and the UK was “extremely rapid” and said earlier restrictions could have had a mitigating effect.

It is possible an earlier lockdown from countries with a high burden of cases, such as Italy, and other measures such as quarantine of travellers from high-risk areas, might have prevented escalation of the outbreak and multiple clusters of ongoing community transmission.

Tracking the new coronavirus using sequencing and genomic epidemiological analysis will help to inform our current response and the effect of public health interventions in real-time and is a tool that can be used to understand future infectious disease outbreaks of this nature.

The study investigated the emergence of the virus in Scotland during March.

The researchers obtained full genome sequences from 1,314 individuals using next-generation sequencing technology, in real-time, of 20% of all confirmed diagnoses of the disease.

Thomson added:

As the number of cases continues to rise in Scotland, our sequence data provide a baseline for real-time sequencing of ongoing infections, which can act as a measure for policymakers of the success of current measures including vaccination and contribute to the easing, or tightening, of public health measures.

A national picture of the virus

Dr Kate Templeton, Consultant Clinical Scientist, University of Edinburgh, said:

The introduction of this sequencing approach has been a great collaboration between the University of Glasgow, University of Edinburgh and Public Health Scotland.

The work in both Glasgow and Edinburgh for this study was only possible from joint working with University and NHS scientists.

The ongoing work is reliant on contributions from NHS clinical and diagnostic laboratory staff across Scotland.

Their efforts have helped us build up a truly national picture of the introduction and ongoing spread of the virus and will provide important information to guide policymakers in how to respond to this pandemic.

The study, ‘Genomic epidemiology reveals multiple introductions of SARS-CoV-2 from 3 mainland Europe into Scotland’ is published in Nature Microbiology.

The study was funded by the MRC, UKRI and Wellcome, and is affiliated with the COVID-19 Genomics UK consortium.

Last updated: 27 January 2021

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