Epidemiological, clinical and genomic snapshot of the first 100 B.1.1.7 SARS-CoV-2 cases in Madrid

We present clinical, genomic and epidemiological data on the first 106 cases with the SARS-CoV-2 B.1.1.7 variant in Madrid. Even from the start, the increase of this variant was due to transmission events within the community, some causing extensive clusters, rather than further imports. Most cases developed non-severe disease.