Although HBsAg seroclearance is the established treatment endpoint of CHB, patients would still have low amounts of intrahepatic HBV DNA. Moreover, HBsAg seroclearance via a conventional assay (HBsAg <0.05 IU/mL) does not mean absence of serum HBsAg, but merely serum HBsAg at undetectable levels. Using more sensitive assays, detectable HBsAg can be found in 29.1% to 53.2% of such patients. So despite the continued presence of HBV, the off-treatment durability of HBsAg seroclearance would suggest for treatment cessation, viral replication and viral protein production do not need to be totally absent, but at sufficiently low amounts to permit successful host immune control.