There is no role for routine testing for hepatitis D antigen (HDAg). Because HDV infection suppresses HBV replication, HBeAg is usually absent in patients with chronic HDV infection and HBV DNA levels are lower than in HBV monoinfection (10). Despite virological relapse, follow-up suggested a survival benefit in treated patients who had achieved a 2 log10 decline in HDV RNA by the end of treatment (11). In the MYR 202 study, the now-approved 2-mg dose resulted in undetectable HDV RNA or >2 log reduction in 54% at week 24 and a combination of virologic response as thus defined with alanine transaminase normalization in 21% (15). In the phase 3 MYR 301 study of long-term therapy, 2 mg of BLV and 10 mg of BLV had virologic response (>2 log decline in HDV RNA or undetectable) at week 48 of 71%–76% and HDV RNA undetectable 12%–20% (15).