Children of people infected with hepatitis B virus may have acquired the hepatitis B virus susceptibility gene from their parents. They may share with their parents some inherited immunodeficiency in protection against hepatitis B virus infection. Therefore, close contact in the family after birth is the main route of paternal-infant transmission of hepatitis B. However, the chance of a father transmitting hepatitis B virus to his child is much smaller than that of a mother, about 26% before vaccine use. Since hepatitis B is completely preventable by vaccination of newborns, father-to-child transmission is no longer a major problem in hepatitis B transmission. Jingjun An, Department of Infectious Diseases, Zhengzhou University First Affiliated Hospital
However, newborns must be tested for hepatitis B virus antibodies after completing the full course (3 doses) of hepatitis B vaccination. This is because a small number of infants do not produce sufficient antibodies to the hepatitis B virus after 3 doses of vaccine, and such children may still be infected with the hepatitis B virus. If the antibody titer drops below 10 IU/ml, the child should be given a booster immunization to stimulate the body to become immune to the hepatitis B virus again.
As long as the child has received the hepatitis B vaccine on time and has developed surface antibodies to the hepatitis B virus, the hepatitis B father can have normal contact with his child, make out with him, and do his fatherly duty.