Frequency of hepatitis B surface antigen variants (HBsAg) in hepatitis B virus genotype B and C infected East- and Southeast Asian patients: Detection by the Elecsys ® HBsAg II assay.

•We analysed blood from 898 patients with chronic HBV from China, Vietnam and Korea.•Mutations in hepatitis B surface antigen (HBsAg) MHR are highly prevalent in Asia.•We identified 237 distinct amino acid MHR mutations, including 25 novel mutations.•Sensitivity of the Elecsys® HBsAg II Qualitative assay was 100% in all samples.•Diagnostic and vaccine-induced escape-associated mutations were detected correctly.