RESUMO
The presence of replication-competent HBV DNA in the liver and/or serum of HBsAg-negative individuals is a sufficient and necessary condition for the diagnosis of occult hepatitis B virus infection (OBI). In recent years, Chinese scholars have proposed what is considered a more "rigorous" definition, i.e., on this basis, HBV window period (WP) infection is excluded, which corresponds to a serum HBV DNA level of below the lower limit of detection or a low positive value (< 200 IU/mL). As the definition of WP for HBV infection remains unclear and its duration is highly variable, "HBV DNA < 200 IU/mL" is not the only criterion in OBI patients. Therefore, it is believed that there is still a lack of sufficient basis and operability for the definition of OBI based on "the exclusion of HBV WP infection" and "HBV DNA < 200 IU/mL" as "rigorous" conditions for the diagnosis of OBI.