A. Horizontal
-Parenteral or percutaneous ( blood, blood derivates, contact with infected instruments, including tattoos).
-Physical contact (non-sexual) : intrafamilial, children collectivities;
-Sexual contact.
B. Vertical
-Perinatal (from an infected mother to the child).
In areas with high endemicity, the transmission is mainly vertical, while in those with medium and low endemicity the main transmission is mostly horizontal. The serological selection of blood taken for transfusion has led to the decreasing in incidence of HBsAg and of residual risk of transmission of HVB.
