UK Reports Alpha Variant (B.1.1.7) — 50–70% More Transmissible

UK health officials announce detection of a new 'Variant of Concern,' B.1.1.7 (later named Alpha by WHO), which had been circulating since September in southeast England. Early estimates suggest it is 50–70% more transmissible than the original strain. The UK imposes Tier 4 restrictions in London and the southeast.