Although the viral load of patients with hepatitis B is low, they are still contagious. The size of the contagiousness depends on the viral load, if the viral load is high, the contagiousness is strong. For patients with hepatitis B, even if the clinical examination is negative for the virus, the chances of transmission by the above means are small, but they are still contagious, especially blood transmission. If a patient with hepatitis B minor tri-positive has active viral replication due to virus mutation, the contagiousness will increase, so the patient’s family members need to be careful not to share toothbrushes, razors, etc. They also need to check whether they have hepatitis B surface antibody, and if they don’t or the value is low, they need to be vaccinated against hepatitis B infection.