Analysis of COVID-19 Genomes reveals large numbers of introductions to the UK in March
Approximately 40 lineages of the SARS-CoV-2 virus have been recorded circulating in the UK, some of which have already gone extinct while others thrive. Previously, the different lineages of the single strain of the virus entered the UK through multiple importations from around the globe, including European countries such as Spain, Italy and France.
Now, fewer international lineages remain in the UK and new cases of COVID-19 arise from local spread rather than importation from other countries. The data reports, published by the COVID-19 Genomics UK Consortium (COG-UK), show the value in mapping COVID-19 lineages across the UK to understand how the virus is spreading at national, regional and local levels.
As of 22 May, more than 20,000 viral genomes from positive COVID-19 tests have been sequenced in the UK, which is the largest number of COVID-19 genomes sequenced by any single country affected by the pandemic.
These genome sequences are being generated and utilised by researchers within COG-UK to identify different lineages* of the virus circulating in the UK. Despite recent reports, this volume of sequencing confirms the all COVID-19 cases in the UK share a recent common ancestor from China; all cases are closely related. The lineages identified highlight small changes to the virus that enable monitoring and tracking over time, but do not signal the emergence of new strains at this point in the outbreak.
These data will aid the UK government in understanding patterns of spread in the UK to help focus different interventions in particular areas of the UK to control the spread of the virus and ultimately save lives.
The COVID-19 Genomics UK Consortium (COG-UK) – comprised of the NHS, Public Health Agencies and numerous academic and research institutions – is delivering large scale, rapid sequencing of the SARS-CoV-2 virus from positive COVID-19 samples and sharing intelligence with hospitals, regional NHS centres and the Government.
The latest COG-UK data reports show large numbers of independent introductions of the virus into the UK from around the world, resulting in approximately 40 COVID-19 lineages that are currently, or have been, circulating in the UK. However, recent data suggest new COVID-19 cases in the UK are arising from local spread rather than people travelling to the UK from other countries.
A dynamic lineage assignment method**, developed within the consortium, enables monitoring of SARS-Cov2 dynamics over time within the UK, with data mapped and delivered openly through an interactive web application***.
The data generated through COG-UK will be used to provide virus status reports, including estimates for the reproduction number, at the level of cities or local authorities.
* What is a viral lineage?
When the virus replicates, genetic errors – mutations – happen in the virus’ genome. When comparing viruses, those with shared patterns of mutations are assigned to different lineages. However a new lineage is not the same as a new strain. A new strain must differ from related viruses in significant ways, such as their transmissibility or virulence. Viral lineages can be plotted on a phylogenetic tree, with the branches representing different lineages, to show the evolutionary relationships between the various lineages. This provides insight into how the virus is mutating and spreading.