Saliva

Saliva of people with hepatitis B can contain the hepatitis B virus, but in very low concentrations compared with blood. Injections of infected saliva can transmit the virus, so bite injuries can also spread the disease. There are no reports of people getting hepatitis B from mouth contact with infected CPR manikins or mouthpieces of musical instruments.

能不能说乙肝病毒可从血液转至唾液，但很难从唾液进入血液？如果这样，唾液中的乙肝病毒能存活多久？