EIDD-2801 is an orally bioavailable prodrug of the antiviral nucleoside derivative N4-hydroxycytidine (NHC, EIDD-1931). It is a nucleotide analog inhibitor of RNA-dependent RNA polymerases (RdRps). The compound interferes with the action of viral RNA polymerase. It exerts its antiviral action through introduction of copying errors during viral RNA replication. The active drug incorporates into the genome of RNA viruses, leading to an accumulation of mutations known as viral error catastrophe. The broad-spectrum antiviral agent EIDD-2801 inhibits viral RNA replication in various unrelated RNA viruses including influenza, Ebola, Venezuelan equine encephalitis virus (VEEV) and coronaviruses, including SARS-CoV, MERS-CoV and SARS-CoV-2. EIDD-2801 has the potential for COVID-19, seasonal and pandemic influenza treatment.