SARS-CoV-2 Delta variant, coloured scanning electron micrograph (SEM). Here the delta variant is shown budding (pink dots) from a Caco-2 human gut epithelial cell 24 hours after infection. 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 worldwide. Magnification: x 6000 at 10cm wide. Specimen courtesy of Greg Towers, University College London, UK.