The active compound of Molnupiravir, N4-hydroxycytidine, promotes SARS-CoV-2 mutagenesis

N4-hydroxycytidine (NHC), the active compound of Molnupiravir, was used to treat SARS-CoV-2-infected cells. The drug works by causing false base pairing in the virus's RNA, leading to an 'error catastrophe'. However, this also carries the risk of creating mutated virus progeny. We performed experiment to show that NHC treatment led to numerous mutations and the emergence of antibody escape mutations. Resistance occurred more rapidly than without NHC.