Transmission electron micrograph (TEM) showing B.1.1.7 variant covid-19 coronavirus particles (round) isolated from a patient. The spike protein (blue) allows the virus to bind to host cells and infect them. The B.1.1.7 variant was first identified in the UK in December 2020 and has since been found in other countries. This variant spreads between people much more quickly than other strains, but does not appear to cause more severe disease. Covid-19 is a respiratory infection that can lead to fatal pneumonia.