The Alpha variant, also known as lineage B.1.1.7, is a variant of SARS-CoV-2, the virus that causes COVID-19. One of several variants of concern, the variant is estimated to be 40–80% more transmissible than the wild-type SARS-CoV-2. It was first detected in November 2020 from a sample taken in September in the United Kingdom, and began to spread quickly by mid-December, around the same time as infections surged. This increase is thought to be at least partly because of one or more mutations in the virus' spike protein. The variant is also notable for having more mutations than normally seen.