Pfefferkorn M, et al. - This study was coordinated to determine whether the composition of hepatitis B virus (HBV) surface antigen (HBsAg) improved the identification of inactive HBV carriers (ICs) among HBsAg-positive subjects with different phases of HBV infections. For the identification of the IC stage, quantification of middle surface proteins (MHBs) represented a novel tool, particularly large surface proteins (LHBs).