Nowadays, PEGylated-IFNα-2a (40 kD) [130] and PEGylated-IFNα-2b (12 kD) [131] are commonly used in the clinical treatment of chronic hepatitis B. Clinical trials have shown that the response rate to PEG-IFNα treatment is higher than that of traditional IFN-α (28% vs. 12%), with improved seroconversion rates (37% vs. 25%) and a lower incidence of side effects compared to traditional IFN-α (2% vs. 4%) [132]. This evidence concerns the gene IFNA2 and chronic hepatitis B virus infection.