Molnupiravir impairing SARS-CoV-2 replication, illustration. Molnupiravir is an antiviral drug that increases the frequency of viral RNA mutations and impairs SARS-CoV-2 replication. The viral RNA-dependent RNA polymerase of SARS-CoV-2 (blue) uses the active form of molnupiravir, 帣-d-N4-hydroxycytidine (NHC, purple) triphosphate, as a substrate instead of cytidine triphosphate or uridine triphosphate. NHC induces the incorporation of wrong base pairs in the replicated RNA strand (orange). This causes the coding of non-functional proteins.