@article\{Challen2021,
 author={Robert Challen and  Ellen Brooks-Pollock and  Jonathan M. Read and  Louise Dyson and  Krasimira Tsaneva-Atanasova and  Leon Danon},
 title={{Risk of mortality in patients infected with SARS-CoV-2 variant of concern202012/1: matched cohort study}},
 journal={BMJ},
 volume={372},
 pages={n579},
 year={2021}
}