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

A new SARS-CoV-2 variant, B.1.1.7, emerged in September in the UK, and is responsible for 76.6% of COVID-19 cases.1 This variant has also been reported in another 45 countries, 17 of them European.2,3 B.1.1.7 is considered to have higher transmissibility.4 It carries an unusually high number of specific mutations/deletions, 18, mostly non-synonymous and eight concentrate in the S gene,5 including several which might have relevant functional roles. The 69/70 deletion may be associated to immune response evasion6 and the N501Y substitution increases the affinity to the ACE2 receptor.7 These findings have raised the alarm of having to face a new variant with the potential to accelerate the spr…