SARS-CoV-2 Delta variant. Coloured scanning electron micrograph (SEM). Here the delta variant is shown budding (purple dots) from a Caco-2 human gut epithelial cell (right hand side) 24 hours after infection. The left hand cell is covered in microvilli but is uninfected. SARS-CoV-2 Delta variant took over globally from the alpha variant in 2021. The delta variant has evolved to better replicate in its new human host allowing it to spread between people more efficiently. The coronaviruses take their name from their crown (corona) of surface proteins, which are used to attach and penetrate their host cells. As of mid-September 2021 226, 130, 821 cases and 4, 653, 230 deaths have been recorded world- wide. Magnification x 10000 at 10cm wide. Specimen courtesy of Greg Towers, UCL