Antiviral Drug Resistance segmentation by Type bifurcates the market into Drug Classโnucleoside analogs, non-nucleoside inhibitors, protease inhibitors, integrase inhibitors, fusion/entry blockersโand Resistance Mechanism, covering genotypic target mutation, phenotypic efflux or metabolic bypass, and biofilm-associated shielding. Nucleoside analogs still command the largest share because of their frontline use in cytomegalovirus, HBV and HCV, yet integrase inhibitor resistance is expanding fastest at >9 % CAGR as HIV treatment switches to dolutegravir-based regimens. Within Resistance Mechanism, genotypic target mutation accounts for roughly 55 % of revenue, driven by high sequencing penetration and tailored salvage therapy pricing; phenotypic resistance, though smaller, is accelerating with influenza M2 channel deletion variants. Each subtype feeds directly into assay kit, companion diagnostic and reformulation revenues, collectively determining the overall Antiviral Drug Resistance market size.