The COVID-19 crisis that gripped the UK between September 2020 and June 2021 can be thought of as a series of overlapping epidemics, rather than a single event, say researchers at the Wellcome Sanger Institute, EMBL’s European Bioinformatics Institute (EMBL-EBI) and their collaborators. During this period, the country wrestled with several versions of the SARS-CoV-2