DaaS

Direct-Acting Antivirals (DAAs) are a class of medications used to treat hepatitis C virus (HCV) infection. DAAs act directly on the virus to inhibit replication by targeting nonstructural viral proteins, most commonly NS3/4A protease, NS5A, and NS5B RNA polymerase, rather than relying on immune-modulating therapies alone. This targeted approach enabled all-oral regimens that do not require interferon.

DAA components include NS3/4A protease inhibitors (such as glecaprevir and voxilaprevir), NS5A inhibitors (ledipasvir, velpatasvir, daclatasvir, and pibrentasvir), and NS5B polymerase inhibitors (sofosbuvir). Many regimens combine agents from different classes. Pan-genotypic regimens such as sofosbuvir/velpatasvir and glecaprevir/pibrentasvir treat most HCV genotypes, typically over 8 to 12 weeks. Other regimens may be chosen for specific genotypes, prior treatment history, or the presence of cirrhosis, and may last 12 to 24 weeks.

Efficacy is high, with sustained virologic response (SVR) rates commonly exceeding 95% in clinical practice. DAAs are generally well tolerated, with mild to moderate side effects such as fatigue or headache being most common. They require assessment for potential drug interactions (notably with antiretrovirals in HIV coinfection, anticoagulants, and acid-reducing agents) and for liver disease status.

Resistance-associated substitutions can influence regimen choice in some patients, especially after prior DAA exposure. Despite their effectiveness, successful eradication of HCV via DAAs reduces disease progression risk but does not eliminate all liver-related risks, underscoring the need for ongoing care and screening for hepatocellular carcinoma in those with cirrhosis.