Rare HBV Genotypes and Clinically Relevant Mutations of HBV and HCV During the COVID-19 Pandemic in a National Reference Outpatient Clinic in Rio de Janeiro, Brazil.

Chronic hepatitis B and C are major causes of cirrhosis, hepatocellular carcinoma, and liver-related mortality worldwide. The genetic diversity of hepatitis B virus (HBV) and hepatitis C virus (HCV) influences disease progression, diagnosis, vaccine response, and antiviral treatment. Periods of healthcare disruption, such as the COVID-19 pandemic, reinforce the importance of molecular surveillance to monitor viral genotypes and clinically relevant mutations. This study described the distribution of HBV and HCV genotypes and mutations in Rio de Janeiro, Brazil, during the COVID-19 pandemic. A cross-sectional study included 25 patients (15 HBV and 10 HCV) recruited between 2020 and 2022. Viral nucleic acids were amplified and sequenced by Sanger methodology, and mutations were analyzed using the Geno2pheno platform. HBV genotype A predominated (67%), comprising subgenotypes A1 (40%) and A2 (27%), followed by the rare genotypes B1 (13%), F2 (13%), and G (7%). Among HCV-infected individuals, genotypes 1a (40%) and 1b (30%) predominated, followed by genotypes 4 (20%) and 2 (10%). HBV immune escape mutations (Y100C and T126S) and unusual insertions in the S and RT domains were identified. In HCV, the substitutions C316Y, C316N, and S282R were detected. These findings highlight the importance of molecular surveillance for detecting clinically relevant viral variants.