Nucleoside or nucleotide antivirals are a common first-line treatment for viral diseases, acting as direct inhibitors of viral replication and transcription. The nucleoside GS-441524 and its prodrug remdesivir have shown broad-spectrum antiviral activity against several virus families, including Flaviviridae, Filoviridae, Pneumoviridae, paramyxoviruses and Coronaviridae.