Hepatitis B is negative for both half pairs within half a year, and this time the test is positive for hepatitis B surface antigen, and this time it is an acute hepatitis B infection. If hepatitis B surface antigen is found positive in the first examination, the following manifestations are considered to be the possibility of chronicity: 1, there are signs of chronic liver disease, such as palms of the liver, spider nevus and face of liver disease; 2, liver ultrasound suggests that the liver echogenicity is uneven and the surface of the liver is blunt and not smooth; 3, liver biopsy suggests that the degree of fibrosis is more than grade 2, and the absence of the above manifestations can not be characterized as acute or chronic, and it is possible to observe the chronicity dynamically for half a year, and if it is still positive after half a year, it will be chronic. If the surface antigen of hepatitis B is still positive after half a year, then it is chronic hepatitis B infection.