Hepatitis B can be detected by a blood test, but it should be noted that the test refers to a blood test for the five items of hepatitis B, also known as hepatitis B two and a half, rather than routine blood tests, blood biochemistry and other tests. The first pair of the hepatitis B two-and-a-half test refers to surface antigen and surface antibody, the second pair is e antigen and e antibody, and the half refers to core antibody. This test can reflect whether the body is infected with the hepatitis B virus, but to get a full picture of the infection, it is usually combined with HBV-DNA quantification (also a blood test), which can better reflect the replication of the virus in the body. For the examination of hepatitis B two pairs of half, usually expressed as 1.HBsAg (hepatitis B surface antigen), 2.HBsAb (hepatitis B surface antibody), 3.HBeAg (hepatitis B e antigen), 4.HBeAb (hepatitis B e antibody), 5.HBcAb (hepatitis B core antibody), for the occurrence of infection, the following judgment can be made: 1, 1, 3, 5 positive items indicate that the infection is a major triple-positive The positive items 1, 4 and 5 indicate that the infection is a minor triplet, which generally indicates that the virus replicates relatively slowly and is relatively less infectious; 3, 2 positive items alone indicate that the original hepatitis B infection or hepatitis B vaccination; 4, 1, 5 or 4, 5 positive items indicate that the infection is in progress or in the process of recovery; 5, 1, 3 positive items indicate that the infection is in progress and should be treated promptly; 6. 5, 1, 3 positive indicates that the infection is in progress and should be treated promptly; 6, 2, 4, 5 positive indicates recovery from acute hepatitis B infection.