Illustration of antiviral drug Molnupiravir (spheres, centre) incorporating itself into SARS-CoV-2 RNA strand. Molnupiravir is a nucleoside analogue of cytidine and uridine. The drug is inserted into the RNA strand instead of cytidine or uridine. The coronavirus's proofreading enzymes that check for mutations do not recognise Molnupiravir has been inserted instead. This causes RNA polymerase (pink, blue and white) to make faulty copies of the faulty RNA strand that can then only code for non-functional proteins. Molnupiravir has been approved for use in the UK for patients with moderate to mild Covid-19 with other risk factors such obesity, obesity, older age and diabetes mellitus.