Illustration of the spike protein (red) from the new variant B117 of the SARS-CoV-2 coronavirus, the cause of the respiratory illness Covid-19. The main mutations of the new variant are labelled. The spike protein binds to angiotensin converting enzyme 2 (ACE2, blue) in the host cell membrane, mediating viral entry to the host cell. B117 was first identified in the UK in December 2020 and has since been found in other countries. B117 spreads between people much more quickly than other strains, but does not appear to cause more severe disease.