Research Briefing
How and why do new variants arise?
The Covid-19 disease is caused by the severe acute respiratory syndrome coronavirus 2 virus, abbreviated to SARS-CoV-2.
When a virus replicates, mutations often occur while its genetic material is being copied. These often have no effect on the behaviour of the virus. Sometimes, however, these mutations result in changes which give this new version of the virus (usually called a strain or variant) distinct characteristics as compared to the original virus. These characteristics may change the way the virus behaves, such as making it more transmissible, causing more severe symptoms or meaning that treatments or vaccines are less effective.
A new variant might be identified as a ‘variant under investigation’ or a ‘variant of concern’. The UK Health Security Agency (UKHSA) defines these terms:
The Covid-19 Genomics UK Consortium (COG-UK) carries out the sequencing of SARS-CoV-2 variants, in collaboration with UK public health agencies, academic institutions, the Wellcome Sanger Institute, Lighthouse Labs and NHS laboratories. The UK Health Security Agency’s New Variant Assessment Platform aims to support other countries strengthen their genomic sequencing capacity. This could be by building on existing infrastructure or sequencing and analysing samples in the UK if there is no in-country capability.
For a more detailed discussion about Covid-19 variants, see the Parliamentary Office of Science and Technology’s briefing, SARS-CoV-2 virus variants: a year into the COVID-19 pandemic.