Illustration of antiviral drug Molnupiravir (ball and stick model) incorporating itself into a SARS-CoV-2 RNA (ribonucleic acid, yellow) 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, which check for mutations in the RNA strand, do not recognise that Molnupiravir has been inserted instead. This causes RNA polymerase to make copies of the faulty RNA strand, which encodes 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.